Hickson 58 and a very strange background galaxy

This may be the busiest field I've every imaged. It certainly resulted in the most complex annotated image that took me several times longer than usual. Fortunately I'd worked ahead a bit knowing this was coming. The field contains Hickson 58, a group of 5 or maybe 8 galaxies many, or all, of which made the NGC catalog as well as two rather nearby Abell galaxy clusters, #1354 at the bottom and #1356 at the top. It also contains many galaxies not in any of these three groups, some of which are quite interesting. Add in that some of the NGC galaxies have two different NGC numbers and things get even more complex.

I'll start with Hickson 58 as that was my target. It is listed as having 8 members at NED and 5 everywhere else and is about 300 million light-years distant in the constellations of Virgo and Leo -- the dividing line is above NGC 3822/3848 and below NGC 3819. The problem is NED lists only 5 members, all NGC galaxies so I can't tell what the other three are or if that is even right. No other source I found says 8. The major ones are NGC 3822/3848, and NGC NGC 3825/3852. Both found my William Herschel on March 15, 1784. So why two designations for each? Here's the explanation at the NGC project:

"NGC 3848 is probably NGC 3822, and NGC 3852 is probably NGC 3825. The
two questionable identifications are a pair found by William Herschel on 15
March 1784, III 35 and III 36. He describes them as ``Two on parallel, 3 or 4
arcmin distant. Both eF, vS,'' and assigns a single position to the pair.

Dreyer, in the Notes to his 1912 edition of WH's papers, claims for N3848,
``Observed by Bigourdan, place correct.'' For N3852, he says, ``RA possibly 1
minute too great (see II 64 [NGC 4352]). Not found by Bigourdan.''

This is curious, as Bigourdan clearly states ``Not seen, at least in a sure
way'' for N3848, and ``Not seen'' for N3852. Perhaps there is a note in one
of Bigourdan's Comptes Rendus papers. In any case, Bigourdan has precise
measurements for NGC 3822 and NGC 3825, and identifies them correctly. They
are 2 minutes west (not 1 minute) of WH's positions for N3848 and N3852, and
they match WH's description well."

NGC 3822/3848 is member A of the HCG 58 group and classed as Sb though I've seen S0 (NGC project says S0?) for it that doesn't seem reasonable to me.

NGC 3825/52 is member B of HCG 58. While redshift puts it as a member of the group its Tully Fisher distance estimate is wildly different at nearly 500 million light-years. So far off I didn't include it in the annotated version.

NGC 3817 is HCG 58C and is considered a triple galaxy. ASK 272459 is on the left and SDSS J114151.70+101809.0 on the right. Buried in the glow of it is a quasar candidate shown on the annotated image. The galaxy has no redshift listed at NED so may or may not be a companion. The left galaxy has virtually the same redshift so likely is a satellite of the main galaxy. The main galaxy is classed as SB0/a at NED and SB0-a at the NGC project. It was discovered by John Herschel on January 18, 1828.

NGC 3819 is HCG 058D. NED lists it as E1 while the NGC Project says E. It was found by John Hershel on January 18, 1828

NGC 3820 is HCG 058E. Ned and the NGC project lists it as Sbc. Its discovery came later on April 29, 1865 by Heinrich d'Arrest.

The only other NGC galaxy is in the lower left corner. It is classed as Sc. It was discovered on April 15, 1784 by William Herschel. While not considered part of Hickson 58 it does lie at about the same distance so likely is part of the same group. It's too far from the others to meet Hickson's compact requirement.

The two Abell cluster's center positions are shown on the annotated image. Abell 1354 is listed as being morphology class III which means it lacks any type of a central large galaxy and is rather disorganized with little concentration. Though ASK 272855 isn't far from the center and larger than the rest there are others nearly as big scattered in th 14 minute field. Abell 1356 is class II-III. Class II clusters are more organized with some condensation toward galaxies not quite large enough to be considered Cd or a Bright Cluster Galaxy. Abell 1356 would be somewhere between II and III. To me it is very similar to 1354 in that it has two rather large galaxies not far from its center, LEDA 139664 and ASK 272849 that aren't much larger or brighter than several others in the group. Several other galaxy groups are seen throughout the image.

One galaxy I wanted to know more about is MAPS-NGP O-494_053290. It is to the east northeast of NGC 3825/3852. It lies close to ASK 273268 but are they at the same distance and thus related? I find no redshift or other distance estimate for the MAPS galaxy. It has such highly warped arms I wish we could get a closer look at it.

Conditions went to pot on this one several times while I was trying to get its data. Especially troublesome was he blue data that got hit by clouds and bad seeing each time. The bad seeing was so bad it created huge stars about 7" FWHM rather than the 3" for the red and green stars. I tried on 4 occasions all failed. I used the two best blue frames but between cloud dimming and the seeing I ended up with blue rings around even rather red stars that no amount of deconvolution could seem to cure. I suspect the galaxies, while rather red are shown more red than they really are due to the dearth of blue data.

Even the luminance was hard hit by thick haze. I used the 6 best frames but my limiting magnitude is a good 1.5 magnitudes brighter than normal thanks to the haze. While that was better some nights I tried for the blue data the seeing was awful so I didn't even try luminance those nights. Instead of trying for good blue I might have been better off to take bad red and green. Sounds crazy but it often works better than waiting for a good night for the third color that never comes.

14" LX200R @ f/10, L=6x10' RGB=2x10', STL-11000XM, Paramount ME

Rick

Rick,

that's a crowded field indeed. I think my favourite is NGC 3833 in the lower
left corner. Good that you could squeeze it in.

Stefan

"WA0CKY" schrieb im Newsbeitrag ...


This may be the busiest field I've every imaged. It certainly resulted
in the most complex annotated image that took me several times longer
than usual. Fortunately I'd worked ahead a bit knowing this was coming.
The field contains Hickson 58, a group of 5 or maybe 8 galaxies many,
or all, of which made the NGC catalog as well as two rather nearby Abell
galaxy clusters, #1354 at the bottom and #1356 at the top. It also
contains many galaxies not in any of these three groups, some of which
are quite interesting. Add in that some of the NGC galaxies have two
different NGC numbers and things get even more complex.

I'll start with Hickson 58 as that was my target. It is listed as
having 8 members at NED and 5 everywhere else and is about 300 million
light-years distant in the constellations of Virgo and Leo -- the
dividing line is above NGC 3822/3848 and below NGC 3819. The problem is
NED lists only 5 members, all NGC galaxies so I can't tell what the
other three are or if that is even right. No other source I found says
8. The major ones are NGC 3822/3848, and NGC NGC 3825/3852. Both found
my William Herschel on March 15, 1784. So why two designations for
each? Here's the explanation at the NGC project:

"NGC 3848 is probably NGC 3822, and NGC 3852 is probably NGC 3825.
The
two questionable identifications are a pair found by William Herschel
on 15
March 1784, III 35 and III 36. He describes them as ``Two on
parallel, 3 or 4
arcmin distant. Both eF, vS,'' and assigns a single position to the
pair.

Dreyer, in the Notes to his 1912 edition of WH's papers, claims for
N3848,
``Observed by Bigourdan, place correct.'' For N3852, he says, ``RA
possibly 1
minute too great (see II 64 [NGC 4352]). Not found by Bigourdan.''

This is curious, as Bigourdan clearly states ``Not seen, at least in
a sure
way'' for N3848, and ``Not seen'' for N3852. Perhaps there is a note
in one
of Bigourdan's Comptes Rendus papers. In any case, Bigourdan has
precise
measurements for NGC 3822 and NGC 3825, and identifies them
correctly. They
are 2 minutes west (not 1 minute) of WH's positions for N3848 and
N3852, and
they match WH's description well."

NGC 3822/3848 is member A of the HCG 58 group and classed as Sb though
I've seen S0 (NGC project says S0?) for it that doesn't seem reasonable
to me.

NGC 3825/52 is member B of HCG 58. While redshift puts it as a member of
the group its Tully Fisher distance estimate is wildly different at
nearly 500 million light-years. So far off I didn't include it in the
annotated version.

NGC 3817 is HCG 58C and is considered a triple galaxy. ASK 272459 is on
the left and SDSS J114151.70+101809.0 on the right. Buried in the glow
of it is a quasar candidate shown on the annotated image. The galaxy
has no redshift listed at NED so may or may not be a companion. The
left galaxy has virtually the same redshift so likely is a satellite of
the main galaxy. The main galaxy is classed as SB0/a at NED and SB0-a
at the NGC project. It was discovered by John Herschel on January 18,
1828.

NGC 3819 is HCG 058D. NED lists it as E1 while the NGC Project says E.
It was found by John Hershel on January 18, 1828

NGC 3820 is HCG 058E. Ned and the NGC project lists it as Sbc. Its
discovery came later on April 29, 1865 by Heinrich d'Arrest.

The only other NGC galaxy is in the lower left corner. It is classed as
Sc. It was discovered on April 15, 1784 by William Herschel. While not
considered part of Hickson 58 it does lie at about the same distance so
likely is part of the same group. It's too far from the others to meet
Hickson's compact requirement.

The two Abell cluster's center positions are shown on the annotated
image. Abell 1354 is listed as being morphology class III which means it
lacks any type of a central large galaxy and is rather disorganized with
little concentration. Though ASK 272855 isn't far from the center and
larger than the rest there are others nearly as big scattered in th 14
minute field. Abell 1356 is class II-III. Class II clusters are more
organized with some condensation toward galaxies not quite large enough
to be considered Cd or a Bright Cluster Galaxy. Abell 1356 would be
somewhere between II and III. To me it is very similar to 1354 in that
it has two rather large galaxies not far from its center, LEDA 139664
and ASK 272849 that aren't much larger or brighter than several others
in the group. Several other galaxy groups are seen throughout the
image.

One galaxy I wanted to know more about is MAPS-NGP O-494_053290. It is
to the east northeast of NGC 3825/3852. It lies close to ASK 273268 but
are they at the same distance and thus related? I find no redshift or
other distance estimate for the MAPS galaxy. It has such highly warped
arms I wish we could get a closer look at it.

Conditions went to pot on this one several times while I was trying to
get its data. Especially troublesome was he blue data that got hit by
clouds and bad seeing each time. The bad seeing was so bad it created
huge stars about 7" FWHM rather than the 3" for the red and green stars.
I tried on 4 occasions all failed. I used the two best blue frames but
between cloud dimming and the seeing I ended up with blue rings around
even rather red stars that no amount of deconvolution could seem to
cure. I suspect the galaxies, while rather red are shown more red than
they really are due to the dearth of blue data.

Even the luminance was hard hit by thick haze. I used the 6 best frames
but my limiting magnitude is a good 1.5 magnitudes brighter than normal
thanks to the haze. While that was better some nights I tried for the
blue data the seeing was awful so I didn't even try luminance those
nights. Instead of trying for good blue I might have been better off to
take bad red and green. Sounds crazy but it often works better than
waiting for a good night for the third color that never comes.

14" LX200R @ f/10, L=6x10' RGB=2x10', STL-11000XM, Paramount ME

Rick


--
WA0CKY