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My second exoplanet transit in the bag
Well half in the bag at least.
I managed to catch the egress of recently announced HD189733b on Friday using just a modified webcam but missed the ingress window tonight because of cloud cover. http://mysite.wanadoo-members.co.uk/..._HD189733b.htm This is the easiest exoplanet for amateurs to date. Nice and deep at 3% , a bright mag 7 parent star and a good matching comparison star nearby. It is easy to find too, near M27. Robin ---------------------------------------------------------------------------- - 54.75N 3.24W http://www.leadbeaterhome.fsnet.co.uk/astro.htm ---------------------------------------------------------------------------- - |
#2
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My second exoplanet transit in the bag
How are you able to measure magnitude so accurately? Seems a real
task---nice job. Doink "Robin Leadbeater" wrote in message ... Well half in the bag at least. I managed to catch the egress of recently announced HD189733b on Friday using just a modified webcam but missed the ingress window tonight because of cloud cover. http://mysite.wanadoo-members.co.uk/..._HD189733b.htm This is the easiest exoplanet for amateurs to date. Nice and deep at 3% , a bright mag 7 parent star and a good matching comparison star nearby. It is easy to find too, near M27. Robin ---------------------------------------------------------------------------- - 54.75N 3.24W http://www.leadbeaterhome.fsnet.co.uk/astro.htm ---------------------------------------------------------------------------- - |
#3
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Well done Robin - nice to see someone is actually observing on this forum;-)
Nytecam Quote:
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My second exoplanet transit in the bag
"Doink" wrote in message ... How are you able to measure magnitude so accurately? Seems a real task---nice job. Doink High absolute accuracy is not so important in transit measurements, just the ability to keep everthing stable enough to measure small changes over a few hours. This is done by comparing the brightness of the varying star in the images with a nearby reference star . Robin |
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My second exoplanet transit in the bag
Robin,
Many congrats on the light curve and a big thanks for the heads-up. I will pursue something similar in a couple of weeks when I will have a favourable transit for my location. Clear skies! Anthony. Robin Leadbeater wrote: Well half in the bag at least. I managed to catch the egress of recently announced HD189733b on Friday using just a modified webcam but missed the ingress window tonight because of cloud cover. http://mysite.wanadoo-members.co.uk/..._HD189733b.htm This is the easiest exoplanet for amateurs to date. Nice and deep at 3% , a bright mag 7 parent star and a good matching comparison star nearby. It is easy to find too, near M27. Robin ---------------------------------------------------------------------------- - 54.75N 3.24W http://www.leadbeaterhome.fsnet.co.uk/astro.htm ---------------------------------------------------------------------------- - |
#6
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My second exoplanet transit in the bag
Robin Leadbeater wrote:
"Doink" wrote in message ... How are you able to measure magnitude so accurately? Seems a real task---nice job. Doink High absolute accuracy is not so important in transit measurements, just the ability to keep everthing stable enough to measure small changes over a few hours. This is done by comparing the brightness of the varying star in the images with a nearby reference star . Robin, Typically with photometry we need two reference stars (comparison and calibration). Which star(s) did you use? Anthony. Robin |
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My second exoplanet transit in the bag
"Anthony Ayiomamitis" wrote in message ... Robin Leadbeater wrote: "Doink" wrote in message ... How are you able to measure magnitude so accurately? Seems a real task---nice job. Doink High absolute accuracy is not so important in transit measurements, just the ability to keep everthing stable enough to measure small changes over a few hours. This is done by comparing the brightness of the varying star in the images with a nearby reference star . Robin, Typically with photometry we need two reference stars (comparison and calibration). Which star(s) did you use? Hi Anthony, It is nice to have an additional check star to make sure everything is stable but you can get away with just one comparison star. In this case (unlike TrES-1) I had to make do with just one as there were no other suitable stars close enough, though you might find some if you have a wider field. I used SAO 88067 which is similar in same magnitude to HD189733 (important when you have only 8 bits to play with!) and a good colour match to minimise differential extinction issues. The Vmags shown on the image are published values. Good luck with your measurements Robin |
#8
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My second exoplanet transit in the bag
nice work.
Robin Leadbeater wrote: "Anthony Ayiomamitis" wrote in message ... Robin Leadbeater wrote: "Doink" wrote in message ... How are you able to measure magnitude so accurately? Seems a real task---nice job. Doink High absolute accuracy is not so important in transit measurements, just the ability to keep everthing stable enough to measure small changes over a few hours. This is done by comparing the brightness of the varying star in the images with a nearby reference star . Robin, Typically with photometry we need two reference stars (comparison and calibration). Which star(s) did you use? Hi Anthony, It is nice to have an additional check star to make sure everything is stable but you can get away with just one comparison star. In this case (unlike TrES-1) I had to make do with just one as there were no other suitable stars close enough, though you might find some if you have a wider field. I used SAO 88067 which is similar in same magnitude to HD189733 (important when you have only 8 bits to play with!) and a good colour match to minimise differential extinction issues. The Vmags shown on the image are published values. Good luck with your measurements Robin |
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