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ASTRO: Arp 289 and its mystery plumes
Arp 289/NGC 3981 is a spiral galaxy in far eastern Crater just barely in
Crater rather than Corvus. At almost 20 degrees south it is the most southern Arp galaxy I've been able to image. It's distance is put at about 100 million light-years by red shift and about 75 million by other methods, mostly Tully-Fisher. Arp put it in his category of Double Galaxies with wind effects. His comment reads: "Very faint diffuse streamers." NED classes it as SAB(s)bc pec. The problem is that most sources don't see a second galaxy. Of the notes at NED only a very old one (1968) about the time of Arp's atlas speaks of it being a M51 like galaxy. Apparently Arp and the note are referring to the blue blob at the south end of the brighter part of the galaxy. The Kanipe-Webb book on the Atlas identifies the blue blob as VV8B. VV stands for the Vorontsov-Velyaminov Interacting Galaxies catalog. But NED shows VV8B as Part of Galaxy, not a separate one. Most today seem to consider the object a massive star forming region in the galaxy rather than a separate galaxy. So what distorted it? Like Arp 184/NGC 1961 I recently processed some say the distortion is just the way this one was made. Even if true how do you explain it was "made" so differently? Hubble hasn't taken but one very underexposed and useless image showing nothing I can recognize so no help there. Kanipe-Webb just leave the issue of one or two galaxies here as open to debate. I can't buy those plumes being just the way this galaxy is. I think it merged with something and the blue blob something left over from the merger which created the huge plumes. I'd love to see some rotational studies of it but couldn't find anything on this. Modern paper (1994 -- latest at NED) read: "The two well-defined principal arms of the grand design type in NGC 3981 have high surface brightness. They can be traced for about half a revolution outward from their origin near the center until they abruptly decrease in surface brightness, become more open, and exhibit a smooth appearance. It is the plume-like appearance of the very faint outer "arms" that gives the notation (tides?) in the classification, although no companion is present. The designation simply describes the morphology not the cause, which probably is not interaction via an encounter but rather is endemic to the galaxy. The heavy main print shows faint HII regions in the outer extensions of the inner arms and in a separate outer arm not connected with the two main inner arms. This third faint outer arm can be faintly seen as a straight segment along the major axis (at the top of the facing print) which then sweeps at a large pitch angle to the right in the orientation of the image here." 1968 paper says: "Third, after M 51 and NGC 7752-3, classical example of interacting galaxies, the bridges to one of them being the spiral arms of the other, caught by a companion. It is now well-established that M 51 is not unique of its kind, but in its time was an important proof of the generality of the composition and origin of spiral arms and bridges between galaxies. Type: vB - Sbt, Morg - fS6. Photo: VV Atlas No. 8; Arp No. 289. Companion here of type Irr?." M51 is Arp 85, NGC 7752-3 is Arp 86 which is a true M51 type galaxy pair. Neither paper mentions merger so maybe I'm way off base. Still I like the idea. Being so far south my image is rather poor. If seeing would hold this low for several nights I could take a pure RGB image which would be much clearer as I could remove the prism effect that so elongates the stars in my luminance channel. Even Registar had trouble aligning the color channels. I probably should have run them through a second time as there's still some nasty prism colors in the corners. Most of which I removed by brute force processing, that is, clone it out. This prism distortion greatly reduced my resolution. Most nights I can't go this low at all so I'm just happy I could get this result. Due to atmospheric absorption this low a lot of light was lost. Even with 60 minutes rather than my normal 40 I couldn't go nearly as deep as normal. Still, I went nearly as deep as most images on the web taken by more southerly located telescopes. The galaxy is out of the Sloan survey field so there's a dearth of information on the other galaxies in the field. The bright oval red galaxy in the upper left corner is MCG -03-31-003, a SAB0 galaxy with a red shift virtually the same as Arp 289. It is likely a member of the same group as Arp 289. I see no distortion to it so it likely has nothing to do with the distortion of Arp 289, just an innocent bystander. Just below at at the 5:30 position is a very tiny, likely dwarf galaxy, [MPP88] 1154-1935. It has a very small redshift putting it possibly much closer, say 20 million-light years away. If true it is a very tiny galaxy. I have some trouble with this. It likely is further away than its pure red shift indicates. MPP is the Monk Penston Pettini galaxy catalog. I don't know what characteristic it is using for deciding what galaxies to include. No other catalog lists this galaxy that NED has in its database. The "large" spiral galaxy half way down the left edge of my image is ESO 572- G 024. It is classed as SBd?. It's redshift is also about the same as Arp 289. Likely another member of its group but again looks quite undisturbed. A couple more likely members of the group are out of the top of my frame. For some reason I thought they were lower so moved the galaxy up. Think I was looking at the declination and assuming it was positive rather than negative. I've done that before. So I missed them. Just more smudges so not much missed. The only other "interesting" galaxy in the image is the smudge of a galaxy toward the right center of the image. It is ESO 572- G 016. Nothing much is known about it. The rest of the galaxies in the image carry unusual catalog names and no red shift distance if they are listed at all, most aren't. Arp's image oriented the same as mine for a change: http://nedwww.ipac.caltech.edu/level...ig_arp289.jpeg 14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
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ASTRO: Arp 289 and its mystery plumes
Rick,
very good image for such a southern object. Btw, do you have any recommendations for southern Arp galaxies that I could image at the end of May/ beginning of June in Namibia? I'd like to get some exotic stuff there in addition to the "stars" of the southern sky ;-) I'll have a Meade 14" ACF scope in the second week there btw (first week is a 12" ASA astrograph on an ASA DDM85 mount, can't wait to get my fingers on that one ;-) Stefan "Rick Johnson" schrieb im Newsbeitrag ster.com... Arp 289/NGC 3981 is a spiral galaxy in far eastern Crater just barely in Crater rather than Corvus. At almost 20 degrees south it is the most southern Arp galaxy I've been able to image. It's distance is put at about 100 million light-years by red shift and about 75 million by other methods, mostly Tully-Fisher. Arp put it in his category of Double Galaxies with wind effects. His comment reads: "Very faint diffuse streamers." NED classes it as SAB(s)bc pec. The problem is that most sources don't see a second galaxy. Of the notes at NED only a very old one (1968) about the time of Arp's atlas speaks of it being a M51 like galaxy. Apparently Arp and the note are referring to the blue blob at the south end of the brighter part of the galaxy. The Kanipe-Webb book on the Atlas identifies the blue blob as VV8B. VV stands for the Vorontsov-Velyaminov Interacting Galaxies catalog. But NED shows VV8B as Part of Galaxy, not a separate one. Most today seem to consider the object a massive star forming region in the galaxy rather than a separate galaxy. So what distorted it? Like Arp 184/NGC 1961 I recently processed some say the distortion is just the way this one was made. Even if true how do you explain it was "made" so differently? Hubble hasn't taken but one very underexposed and useless image showing nothing I can recognize so no help there. Kanipe-Webb just leave the issue of one or two galaxies here as open to debate. I can't buy those plumes being just the way this galaxy is. I think it merged with something and the blue blob something left over from the merger which created the huge plumes. I'd love to see some rotational studies of it but couldn't find anything on this. Modern paper (1994 -- latest at NED) read: "The two well-defined principal arms of the grand design type in NGC 3981 have high surface brightness. They can be traced for about half a revolution outward from their origin near the center until they abruptly decrease in surface brightness, become more open, and exhibit a smooth appearance. It is the plume-like appearance of the very faint outer "arms" that gives the notation (tides?) in the classification, although no companion is present. The designation simply describes the morphology not the cause, which probably is not interaction via an encounter but rather is endemic to the galaxy. The heavy main print shows faint HII regions in the outer extensions of the inner arms and in a separate outer arm not connected with the two main inner arms. This third faint outer arm can be faintly seen as a straight segment along the major axis (at the top of the facing print) which then sweeps at a large pitch angle to the right in the orientation of the image here." 1968 paper says: "Third, after M 51 and NGC 7752-3, classical example of interacting galaxies, the bridges to one of them being the spiral arms of the other, caught by a companion. It is now well-established that M 51 is not unique of its kind, but in its time was an important proof of the generality of the composition and origin of spiral arms and bridges between galaxies. Type: vB - Sbt, Morg - fS6. Photo: VV Atlas No. 8; Arp No. 289. Companion here of type Irr?." M51 is Arp 85, NGC 7752-3 is Arp 86 which is a true M51 type galaxy pair. Neither paper mentions merger so maybe I'm way off base. Still I like the idea. Being so far south my image is rather poor. If seeing would hold this low for several nights I could take a pure RGB image which would be much clearer as I could remove the prism effect that so elongates the stars in my luminance channel. Even Registar had trouble aligning the color channels. I probably should have run them through a second time as there's still some nasty prism colors in the corners. Most of which I removed by brute force processing, that is, clone it out. This prism distortion greatly reduced my resolution. Most nights I can't go this low at all so I'm just happy I could get this result. Due to atmospheric absorption this low a lot of light was lost. Even with 60 minutes rather than my normal 40 I couldn't go nearly as deep as normal. Still, I went nearly as deep as most images on the web taken by more southerly located telescopes. The galaxy is out of the Sloan survey field so there's a dearth of information on the other galaxies in the field. The bright oval red galaxy in the upper left corner is MCG -03-31-003, a SAB0 galaxy with a red shift virtually the same as Arp 289. It is likely a member of the same group as Arp 289. I see no distortion to it so it likely has nothing to do with the distortion of Arp 289, just an innocent bystander. Just below at at the 5:30 position is a very tiny, likely dwarf galaxy, [MPP88] 1154-1935. It has a very small redshift putting it possibly much closer, say 20 million-light years away. If true it is a very tiny galaxy. I have some trouble with this. It likely is further away than its pure red shift indicates. MPP is the Monk Penston Pettini galaxy catalog. I don't know what characteristic it is using for deciding what galaxies to include. No other catalog lists this galaxy that NED has in its database. The "large" spiral galaxy half way down the left edge of my image is ESO 572- G 024. It is classed as SBd?. It's redshift is also about the same as Arp 289. Likely another member of its group but again looks quite undisturbed. A couple more likely members of the group are out of the top of my frame. For some reason I thought they were lower so moved the galaxy up. Think I was looking at the declination and assuming it was positive rather than negative. I've done that before. So I missed them. Just more smudges so not much missed. The only other "interesting" galaxy in the image is the smudge of a galaxy toward the right center of the image. It is ESO 572- G 016. Nothing much is known about it. The rest of the galaxies in the image carry unusual catalog names and no red shift distance if they are listed at all, most aren't. Arp's image oriented the same as mine for a change: http://nedwww.ipac.caltech.edu/level...ig_arp289.jpeg 14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
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ASTRO: Arp 289 and its mystery plumes
Most southerly Arp is Centaurus A. This web page lists them in RA
order. I've not paid much attention to those below my cutoff of 15 degrees. http://arpgalaxy.com/arplist.html I then look them up on a DSS server. http://stdatu.stsci.edu/ Which is down this weekend I see. I like it as I can get the images at 1" per pixel which happens to be my main image scale. I can set it for my image dimensions as well. Still on my too far south list for that once in a decade night are Arp 22 at 11 hours and -19 degrees (probably a bit west by the time you are down there but first target of the night maybe. The other at -24 is Arp 226 at 22 hours so an early morning object. I have a bunch on my Arp like list, most of which I can't recall and with the server down can't check on. I do see however they, like Arp 226 are dawn objects. IC 1438-9 and NGC 7656 are two I've never had seeing that low for but they are late summer to fall objects. Doubt they'd rise until 3:30 or so. Not sure how much dark time you have there. A lot more than I have here that time of the year which is nearly none. Worse for you so a good time to leave. Lots of nice targets for the wide field of the ASA scope. What camera? Yours or can they provide a huge chip one. 11K is about all the 14" can handle but the ASA should handle the largest of today's chips I'd think. I'm looking to go wide field with something atop the 14" but that scope is too big. I couldn't close the roof. 6" is about all I have room for. Hope the weather is better than last year for you. Rick On 2/27/2011 1:49 PM, Stefan Lilge wrote: Rick, very good image for such a southern object. Btw, do you have any recommendations for southern Arp galaxies that I could image at the end of May/ beginning of June in Namibia? I'd like to get some exotic stuff there in addition to the "stars" of the southern sky ;-) I'll have a Meade 14" ACF scope in the second week there btw (first week is a 12" ASA astrograph on an ASA DDM85 mount, can't wait to get my fingers on that one ;-) Stefan "Rick schrieb im Newsbeitrag ster.com... Arp 289/NGC 3981 is a spiral galaxy in far eastern Crater just barely in Crater rather than Corvus. At almost 20 degrees south it is the most southern Arp galaxy I've been able to image. It's distance is put at about 100 million light-years by red shift and about 75 million by other methods, mostly Tully-Fisher. Arp put it in his category of Double Galaxies with wind effects. His comment reads: "Very faint diffuse streamers." NED classes it as SAB(s)bc pec. The problem is that most sources don't see a second galaxy. Of the notes at NED only a very old one (1968) about the time of Arp's atlas speaks of it being a M51 like galaxy. Apparently Arp and the note are referring to the blue blob at the south end of the brighter part of the galaxy. The Kanipe-Webb book on the Atlas identifies the blue blob as VV8B. VV stands for the Vorontsov-Velyaminov Interacting Galaxies catalog. But NED shows VV8B as Part of Galaxy, not a separate one. Most today seem to consider the object a massive star forming region in the galaxy rather than a separate galaxy. So what distorted it? Like Arp 184/NGC 1961 I recently processed some say the distortion is just the way this one was made. Even if true how do you explain it was "made" so differently? Hubble hasn't taken but one very underexposed and useless image showing nothing I can recognize so no help there. Kanipe-Webb just leave the issue of one or two galaxies here as open to debate. I can't buy those plumes being just the way this galaxy is. I think it merged with something and the blue blob something left over from the merger which created the huge plumes. I'd love to see some rotational studies of it but couldn't find anything on this. Modern paper (1994 -- latest at NED) read: "The two well-defined principal arms of the grand design type in NGC 3981 have high surface brightness. They can be traced for about half a revolution outward from their origin near the center until they abruptly decrease in surface brightness, become more open, and exhibit a smooth appearance. It is the plume-like appearance of the very faint outer "arms" that gives the notation (tides?) in the classification, although no companion is present. The designation simply describes the morphology not the cause, which probably is not interaction via an encounter but rather is endemic to the galaxy. The heavy main print shows faint HII regions in the outer extensions of the inner arms and in a separate outer arm not connected with the two main inner arms. This third faint outer arm can be faintly seen as a straight segment along the major axis (at the top of the facing print) which then sweeps at a large pitch angle to the right in the orientation of the image here." 1968 paper says: "Third, after M 51 and NGC 7752-3, classical example of interacting galaxies, the bridges to one of them being the spiral arms of the other, caught by a companion. It is now well-established that M 51 is not unique of its kind, but in its time was an important proof of the generality of the composition and origin of spiral arms and bridges between galaxies. Type: vB - Sbt, Morg - fS6. Photo: VV Atlas No. 8; Arp No. 289. Companion here of type Irr?." M51 is Arp 85, NGC 7752-3 is Arp 86 which is a true M51 type galaxy pair. Neither paper mentions merger so maybe I'm way off base. Still I like the idea. Being so far south my image is rather poor. If seeing would hold this low for several nights I could take a pure RGB image which would be much clearer as I could remove the prism effect that so elongates the stars in my luminance channel. Even Registar had trouble aligning the color channels. I probably should have run them through a second time as there's still some nasty prism colors in the corners. Most of which I removed by brute force processing, that is, clone it out. This prism distortion greatly reduced my resolution. Most nights I can't go this low at all so I'm just happy I could get this result. Due to atmospheric absorption this low a lot of light was lost. Even with 60 minutes rather than my normal 40 I couldn't go nearly as deep as normal. Still, I went nearly as deep as most images on the web taken by more southerly located telescopes. The galaxy is out of the Sloan survey field so there's a dearth of information on the other galaxies in the field. The bright oval red galaxy in the upper left corner is MCG -03-31-003, a SAB0 galaxy with a red shift virtually the same as Arp 289. It is likely a member of the same group as Arp 289. I see no distortion to it so it likely has nothing to do with the distortion of Arp 289, just an innocent bystander. Just below at at the 5:30 position is a very tiny, likely dwarf galaxy, [MPP88] 1154-1935. It has a very small redshift putting it possibly much closer, say 20 million-light years away. If true it is a very tiny galaxy. I have some trouble with this. It likely is further away than its pure red shift indicates. MPP is the Monk Penston Pettini galaxy catalog. I don't know what characteristic it is using for deciding what galaxies to include. No other catalog lists this galaxy that NED has in its database. The "large" spiral galaxy half way down the left edge of my image is ESO 572- G 024. It is classed as SBd?. It's redshift is also about the same as Arp 289. Likely another member of its group but again looks quite undisturbed. A couple more likely members of the group are out of the top of my frame. For some reason I thought they were lower so moved the galaxy up. Think I was looking at the declination and assuming it was positive rather than negative. I've done that before. So I missed them. Just more smudges so not much missed. The only other "interesting" galaxy in the image is the smudge of a galaxy toward the right center of the image. It is ESO 572- G 016. Nothing much is known about it. The rest of the galaxies in the image carry unusual catalog names and no red shift distance if they are listed at all, most aren't. Arp's image oriented the same as mine for a change: http://nedwww.ipac.caltech.edu/level...ig_arp289.jpeg 14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
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ASTRO: Arp 289 and its mystery plumes
Rick,
you can be sure that I will be imaging Centaurus A :-) Arp doesn't seem to have too many southern galaxies in his list. I am hoping to find something similar as NGC 1313 for spring... I will use my Atik 383 with the ASA astrograph. Actually I wouldn't use the STL11000 even if they would lend me one as the 9 micron pixels are much too large for this telescope with only a bit more than one meter focal length. The KAF8300 chip gives a nice scale at almost exactly 1 arcsecond/pixel, which, as can be wittnessed by your images, is a good scale for galaxies. That with a f/3.6 scope and dark skies (and hopefully few clouds) should allow for some good deep images... For piggy-backing on your 14" I would consider the Skywatcher Evostar ED120 plus the fitting 0,85 power reducer/corrector. I have the older Skywatcher ED120 Pro scope and while it does have some blue fringes around (only) blue stars, these can be kept under control by image processing. And the newer ones are rumoured to have better colour correction. This scope is not too expensive and lightweight (a bit more than 5kg), so your Paramount won't have problems to carry them both ;-) At 765mm focal lenghts it should cover a lot of estate with the STL11k; only thing that could go wrong here could be the weight of your camera taxing the focuser too much... Stefan "Rick Johnson" schrieb im Newsbeitrag ster.com... Most southerly Arp is Centaurus A. This web page lists them in RA order. I've not paid much attention to those below my cutoff of 15 degrees. http://arpgalaxy.com/arplist.html I then look them up on a DSS server. http://stdatu.stsci.edu/ Which is down this weekend I see. I like it as I can get the images at 1" per pixel which happens to be my main image scale. I can set it for my image dimensions as well. Still on my too far south list for that once in a decade night are Arp 22 at 11 hours and -19 degrees (probably a bit west by the time you are down there but first target of the night maybe. The other at -24 is Arp 226 at 22 hours so an early morning object. I have a bunch on my Arp like list, most of which I can't recall and with the server down can't check on. I do see however they, like Arp 226 are dawn objects. IC 1438-9 and NGC 7656 are two I've never had seeing that low for but they are late summer to fall objects. Doubt they'd rise until 3:30 or so. Not sure how much dark time you have there. A lot more than I have here that time of the year which is nearly none. Worse for you so a good time to leave. Lots of nice targets for the wide field of the ASA scope. What camera? Yours or can they provide a huge chip one. 11K is about all the 14" can handle but the ASA should handle the largest of today's chips I'd think. I'm looking to go wide field with something atop the 14" but that scope is too big. I couldn't close the roof. 6" is about all I have room for. Hope the weather is better than last year for you. Rick On 2/27/2011 1:49 PM, Stefan Lilge wrote: Rick, very good image for such a southern object. Btw, do you have any recommendations for southern Arp galaxies that I could image at the end of May/ beginning of June in Namibia? I'd like to get some exotic stuff there in addition to the "stars" of the southern sky ;-) I'll have a Meade 14" ACF scope in the second week there btw (first week is a 12" ASA astrograph on an ASA DDM85 mount, can't wait to get my fingers on that one ;-) Stefan "Rick schrieb im Newsbeitrag ster.com... Arp 289/NGC 3981 is a spiral galaxy in far eastern Crater just barely in Crater rather than Corvus. At almost 20 degrees south it is the most southern Arp galaxy I've been able to image. It's distance is put at about 100 million light-years by red shift and about 75 million by other methods, mostly Tully-Fisher. Arp put it in his category of Double Galaxies with wind effects. His comment reads: "Very faint diffuse streamers." NED classes it as SAB(s)bc pec. The problem is that most sources don't see a second galaxy. Of the notes at NED only a very old one (1968) about the time of Arp's atlas speaks of it being a M51 like galaxy. Apparently Arp and the note are referring to the blue blob at the south end of the brighter part of the galaxy. The Kanipe-Webb book on the Atlas identifies the blue blob as VV8B. VV stands for the Vorontsov-Velyaminov Interacting Galaxies catalog. But NED shows VV8B as Part of Galaxy, not a separate one. Most today seem to consider the object a massive star forming region in the galaxy rather than a separate galaxy. So what distorted it? Like Arp 184/NGC 1961 I recently processed some say the distortion is just the way this one was made. Even if true how do you explain it was "made" so differently? Hubble hasn't taken but one very underexposed and useless image showing nothing I can recognize so no help there. Kanipe-Webb just leave the issue of one or two galaxies here as open to debate. I can't buy those plumes being just the way this galaxy is. I think it merged with something and the blue blob something left over from the merger which created the huge plumes. I'd love to see some rotational studies of it but couldn't find anything on this. Modern paper (1994 -- latest at NED) read: "The two well-defined principal arms of the grand design type in NGC 3981 have high surface brightness. They can be traced for about half a revolution outward from their origin near the center until they abruptly decrease in surface brightness, become more open, and exhibit a smooth appearance. It is the plume-like appearance of the very faint outer "arms" that gives the notation (tides?) in the classification, although no companion is present. The designation simply describes the morphology not the cause, which probably is not interaction via an encounter but rather is endemic to the galaxy. The heavy main print shows faint HII regions in the outer extensions of the inner arms and in a separate outer arm not connected with the two main inner arms. This third faint outer arm can be faintly seen as a straight segment along the major axis (at the top of the facing print) which then sweeps at a large pitch angle to the right in the orientation of the image here." 1968 paper says: "Third, after M 51 and NGC 7752-3, classical example of interacting galaxies, the bridges to one of them being the spiral arms of the other, caught by a companion. It is now well-established that M 51 is not unique of its kind, but in its time was an important proof of the generality of the composition and origin of spiral arms and bridges between galaxies. Type: vB - Sbt, Morg - fS6. Photo: VV Atlas No. 8; Arp No. 289. Companion here of type Irr?." M51 is Arp 85, NGC 7752-3 is Arp 86 which is a true M51 type galaxy pair. Neither paper mentions merger so maybe I'm way off base. Still I like the idea. Being so far south my image is rather poor. If seeing would hold this low for several nights I could take a pure RGB image which would be much clearer as I could remove the prism effect that so elongates the stars in my luminance channel. Even Registar had trouble aligning the color channels. I probably should have run them through a second time as there's still some nasty prism colors in the corners. Most of which I removed by brute force processing, that is, clone it out. This prism distortion greatly reduced my resolution. Most nights I can't go this low at all so I'm just happy I could get this result. Due to atmospheric absorption this low a lot of light was lost. Even with 60 minutes rather than my normal 40 I couldn't go nearly as deep as normal. Still, I went nearly as deep as most images on the web taken by more southerly located telescopes. The galaxy is out of the Sloan survey field so there's a dearth of information on the other galaxies in the field. The bright oval red galaxy in the upper left corner is MCG -03-31-003, a SAB0 galaxy with a red shift virtually the same as Arp 289. It is likely a member of the same group as Arp 289. I see no distortion to it so it likely has nothing to do with the distortion of Arp 289, just an innocent bystander. Just below at at the 5:30 position is a very tiny, likely dwarf galaxy, [MPP88] 1154-1935. It has a very small redshift putting it possibly much closer, say 20 million-light years away. If true it is a very tiny galaxy. I have some trouble with this. It likely is further away than its pure red shift indicates. MPP is the Monk Penston Pettini galaxy catalog. I don't know what characteristic it is using for deciding what galaxies to include. No other catalog lists this galaxy that NED has in its database. The "large" spiral galaxy half way down the left edge of my image is ESO 572- G 024. It is classed as SBd?. It's redshift is also about the same as Arp 289. Likely another member of its group but again looks quite undisturbed. A couple more likely members of the group are out of the top of my frame. For some reason I thought they were lower so moved the galaxy up. Think I was looking at the declination and assuming it was positive rather than negative. I've done that before. So I missed them. Just more smudges so not much missed. The only other "interesting" galaxy in the image is the smudge of a galaxy toward the right center of the image. It is ESO 572- G 016. Nothing much is known about it. The rest of the galaxies in the image carry unusual catalog names and no red shift distance if they are listed at all, most aren't. Arp's image oriented the same as mine for a change: http://nedwww.ipac.caltech.edu/level...ig_arp289.jpeg 14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
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ASTRO: Arp 289 and its mystery plumes
I disagree about the small pixels for the ASA. To me a scope like that
is for the huge FOV not resolution or galaxy work. I'd want as large a chip as possible. Coupled with large pixels it can really pull in stuff. Have you seen Tom Davis' site. http://www.tvdavisastropics.com/ He does great things with that camera and scope. Often he uses two 11K cameras. A OSC on a 6" AP f/5.8 APO for color data and the mono one on his f/3.5 12" ASA. Now that's dedication. Of course with only 1 week on both priorities might be different. There's a fellow up here thinking of selling his FSQ106 and getting that scope with a 16803 camera, also 9 micron. If so I am considering giving him an offer for the FSQ though I don't need another 11K and he likely will look to sell it as a package. Weight isn't an issue with the Paramount and he has the focuser modified to carry the 11K's weight so know that's not an issue. But he needs to hold off until I get the daughter out of nursing school and into a job. That's sucking things dry right now. Graduates in May and is 1st in her class so that's about as good as I can hope for. I'm not up on southern galaxies. If it is below about -15 I've not really paid much attention unless it is a common object or an Arp. Most Arp's are quite small in angular size or well known like Centaurus A, M101 etc. I had to look up NGC 1313 as it had vanished from my memory banks. I have all I can handle above -15 degrees. Several years ago had use of a 14" scope in a dome for visual use (not set up for imaging) in New Zealand. Was a rental house that happened to come with the observatory. But with sightseeing by day I didn't have much left for night. By midnight I was dead. Clouds were a big problem as well. The gal (high school science teacher) who owned it had a list of good objects but when we were there in July most were nebula. It was odd to see M104 high in a dark sky in July however. I had no trouble with the "upside down" sky but getting used to what was up at dark took some getting used to. No I didn't spend time on it just noted Corvus high in the sky at dusk much to my amazement. Scorpio directly overhead took some getting used to as well. Wish the weather had given me more time with that scope, 14" f/7 Newtonian so a rather large beast compared to my 14" SCT. Rick On 2/28/2011 3:26 PM, Stefan Lilge wrote: Rick, you can be sure that I will be imaging Centaurus A :-) Arp doesn't seem to have too many southern galaxies in his list. I am hoping to find something similar as NGC 1313 for spring... I will use my Atik 383 with the ASA astrograph. Actually I wouldn't use the STL11000 even if they would lend me one as the 9 micron pixels are much too large for this telescope with only a bit more than one meter focal length. The KAF8300 chip gives a nice scale at almost exactly 1 arcsecond/pixel, which, as can be wittnessed by your images, is a good scale for galaxies. That with a f/3.6 scope and dark skies (and hopefully few clouds) should allow for some good deep images... For piggy-backing on your 14" I would consider the Skywatcher Evostar ED120 plus the fitting 0,85 power reducer/corrector. I have the older Skywatcher ED120 Pro scope and while it does have some blue fringes around (only) blue stars, these can be kept under control by image processing. And the newer ones are rumoured to have better colour correction. This scope is not too expensive and lightweight (a bit more than 5kg), so your Paramount won't have problems to carry them both ;-) At 765mm focal lenghts it should cover a lot of estate with the STL11k; only thing that could go wrong here could be the weight of your camera taxing the focuser too much... Stefan "Rick schrieb im Newsbeitrag ster.com... Most southerly Arp is Centaurus A. This web page lists them in RA order. I've not paid much attention to those below my cutoff of 15 degrees. http://arpgalaxy.com/arplist.html I then look them up on a DSS server. http://stdatu.stsci.edu/ Which is down this weekend I see. I like it as I can get the images at 1" per pixel which happens to be my main image scale. I can set it for my image dimensions as well. Still on my too far south list for that once in a decade night are Arp 22 at 11 hours and -19 degrees (probably a bit west by the time you are down there but first target of the night maybe. The other at -24 is Arp 226 at 22 hours so an early morning object. I have a bunch on my Arp like list, most of which I can't recall and with the server down can't check on. I do see however they, like Arp 226 are dawn objects. IC 1438-9 and NGC 7656 are two I've never had seeing that low for but they are late summer to fall objects. Doubt they'd rise until 3:30 or so. Not sure how much dark time you have there. A lot more than I have here that time of the year which is nearly none. Worse for you so a good time to leave. Lots of nice targets for the wide field of the ASA scope. What camera? Yours or can they provide a huge chip one. 11K is about all the 14" can handle but the ASA should handle the largest of today's chips I'd think. I'm looking to go wide field with something atop the 14" but that scope is too big. I couldn't close the roof. 6" is about all I have room for. Hope the weather is better than last year for you. Rick On 2/27/2011 1:49 PM, Stefan Lilge wrote: Rick, very good image for such a southern object. Btw, do you have any recommendations for southern Arp galaxies that I could image at the end of May/ beginning of June in Namibia? I'd like to get some exotic stuff there in addition to the "stars" of the southern sky ;-) I'll have a Meade 14" ACF scope in the second week there btw (first week is a 12" ASA astrograph on an ASA DDM85 mount, can't wait to get my fingers on that one ;-) Stefan "Rick schrieb im Newsbeitrag ster.com... Arp 289/NGC 3981 is a spiral galaxy in far eastern Crater just barely in Crater rather than Corvus. At almost 20 degrees south it is the most southern Arp galaxy I've been able to image. It's distance is put at about 100 million light-years by red shift and about 75 million by other methods, mostly Tully-Fisher. Arp put it in his category of Double Galaxies with wind effects. His comment reads: "Very faint diffuse streamers." NED classes it as SAB(s)bc pec. The problem is that most sources don't see a second galaxy. Of the notes at NED only a very old one (1968) about the time of Arp's atlas speaks of it being a M51 like galaxy. Apparently Arp and the note are referring to the blue blob at the south end of the brighter part of the galaxy. The Kanipe-Webb book on the Atlas identifies the blue blob as VV8B. VV stands for the Vorontsov-Velyaminov Interacting Galaxies catalog. But NED shows VV8B as Part of Galaxy, not a separate one. Most today seem to consider the object a massive star forming region in the galaxy rather than a separate galaxy. So what distorted it? Like Arp 184/NGC 1961 I recently processed some say the distortion is just the way this one was made. Even if true how do you explain it was "made" so differently? Hubble hasn't taken but one very underexposed and useless image showing nothing I can recognize so no help there. Kanipe-Webb just leave the issue of one or two galaxies here as open to debate. I can't buy those plumes being just the way this galaxy is. I think it merged with something and the blue blob something left over from the merger which created the huge plumes. I'd love to see some rotational studies of it but couldn't find anything on this. Modern paper (1994 -- latest at NED) read: "The two well-defined principal arms of the grand design type in NGC 3981 have high surface brightness. They can be traced for about half a revolution outward from their origin near the center until they abruptly decrease in surface brightness, become more open, and exhibit a smooth appearance. It is the plume-like appearance of the very faint outer "arms" that gives the notation (tides?) in the classification, although no companion is present. The designation simply describes the morphology not the cause, which probably is not interaction via an encounter but rather is endemic to the galaxy. The heavy main print shows faint HII regions in the outer extensions of the inner arms and in a separate outer arm not connected with the two main inner arms. This third faint outer arm can be faintly seen as a straight segment along the major axis (at the top of the facing print) which then sweeps at a large pitch angle to the right in the orientation of the image here." 1968 paper says: "Third, after M 51 and NGC 7752-3, classical example of interacting galaxies, the bridges to one of them being the spiral arms of the other, caught by a companion. It is now well-established that M 51 is not unique of its kind, but in its time was an important proof of the generality of the composition and origin of spiral arms and bridges between galaxies. Type: vB - Sbt, Morg - fS6. Photo: VV Atlas No. 8; Arp No. 289. Companion here of type Irr?." M51 is Arp 85, NGC 7752-3 is Arp 86 which is a true M51 type galaxy pair. Neither paper mentions merger so maybe I'm way off base. Still I like the idea. Being so far south my image is rather poor. If seeing would hold this low for several nights I could take a pure RGB image which would be much clearer as I could remove the prism effect that so elongates the stars in my luminance channel. Even Registar had trouble aligning the color channels. I probably should have run them through a second time as there's still some nasty prism colors in the corners. Most of which I removed by brute force processing, that is, clone it out. This prism distortion greatly reduced my resolution. Most nights I can't go this low at all so I'm just happy I could get this result. Due to atmospheric absorption this low a lot of light was lost. Even with 60 minutes rather than my normal 40 I couldn't go nearly as deep as normal. Still, I went nearly as deep as most images on the web taken by more southerly located telescopes. The galaxy is out of the Sloan survey field so there's a dearth of information on the other galaxies in the field. The bright oval red galaxy in the upper left corner is MCG -03-31-003, a SAB0 galaxy with a red shift virtually the same as Arp 289. It is likely a member of the same group as Arp 289. I see no distortion to it so it likely has nothing to do with the distortion of Arp 289, just an innocent bystander. Just below at at the 5:30 position is a very tiny, likely dwarf galaxy, [MPP88] 1154-1935. It has a very small redshift putting it possibly much closer, say 20 million-light years away. If true it is a very tiny galaxy. I have some trouble with this. It likely is further away than its pure red shift indicates. MPP is the Monk Penston Pettini galaxy catalog. I don't know what characteristic it is using for deciding what galaxies to include. No other catalog lists this galaxy that NED has in its database. The "large" spiral galaxy half way down the left edge of my image is ESO 572- G 024. It is classed as SBd?. It's redshift is also about the same as Arp 289. Likely another member of its group but again looks quite undisturbed. A couple more likely members of the group are out of the top of my frame. For some reason I thought they were lower so moved the galaxy up. Think I was looking at the declination and assuming it was positive rather than negative. I've done that before. So I missed them. Just more smudges so not much missed. The only other "interesting" galaxy in the image is the smudge of a galaxy toward the right center of the image. It is ESO 572- G 016. Nothing much is known about it. The rest of the galaxies in the image carry unusual catalog names and no red shift distance if they are listed at all, most aren't. Arp's image oriented the same as mine for a change: http://nedwww.ipac.caltech.edu/level...ig_arp289.jpeg 14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
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