square_peg
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http://news.yahoo.com/s/ap/20090128/ap_on_sc/sci_hot_planet
Quote:
The star is visible from Earth near the Big Dipper. On Feb. 14, HD80606b will travel between the Earth and its star. There's a 15 percent chance that amateur astronomers using small telescopes could see it swing by, obscuring a tiny part of the star, Laughlin said.
I think variable star observers would be best equipped to see or image this. Got plans for Valentines Day?
--------------------
Tom (Pegster)
DSH-8 (GSO Dob)
15x70 Oberwerks
SVP/ED80
WO 66 Petzval
Sears Discoverer EQ 60/900
8x42 Regals
History is Philosophy teaching by examples.
Thucydides
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btieman
professor emeritus
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Posts: 567
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Thanks for the heads up! I was going to take a shot at something like XO-2 in March. I'm not sure I'm ready to try this one yet...
If I read the predictions from transitsearch.org correctly, it looks like the full transit will take about 24 hours starting midday the 13th and ending midday the 14th. It doesn't look like much hope to be able to measure the mid transit time. Should be able to get comparisons from night to night, though. If the darkening is only a percent or so, though, might be hard to convince anyone you've caught it.
Anyone have any suggestions about how best to go about this? One of my goals is to measure an exo-planet transit...may as well start getting some practice! This one isn't predicted to transit again until June.
Brian
--------------------
CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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walt r
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Reged: 02/13/07
Posts: 3523
Loc: Doylestown, PA
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Brian,
Check Tonny Vanmunster's exoplanet page and the AAVSO's Exoplanet Transit Search Observing Program for starters.
The problem of not being able to catch the entire transit event is good reason for international collaboration. With a number of observers spacer around the globe 24 hour coverage can be obtained. Also any overlapping observations can be combined to improve the SNR and reliability of the observations. This a good reason to submit your photometry sequence to the AAVSO or other supporting organization.
Good luck with this event.
--------------------
Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
Edited by walt r (02/01/09 07:18 PM)
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robin_astro
super member
Reged: 12/18/05
Posts: 164
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Hi,
Quote:
If I read the predictions from transitsearch.org correctly, it looks like the full transit will take about 24 hours starting midday the 13th and ending midday the 14th. It doesn't look like much hope to be able to measure the mid transit time.
It appears the predicted transit time of a central transit is 18 hours, though the actual time could be anywhere from 0 (ie no transit) to 18 hrs as the exact orbit is not known (hence the 15% probablity of a transit) so any observation during the window could be useful and catch either an ingress or egress.
A useful link is Bruce Gary's on line book
"Exoplanet observing for Amateurs"
http://brucegary.net/book_EOA/x.htm
Robin
www.threehillsobservatory.co.uk
--------------------
www.threehillsobservatory.co.uk
Vixen VC200L GPDX Skysensor 2000
Modified web and video cams, Spectrograph
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btieman
professor emeritus
Reged: 07/24/08
Posts: 567
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I've read most of Bruce's book--it is very informative. Tonny's page looks informative as well...I'll give it a read.
If the sky is clear,I'll likely give it a try for a few hours, but, being new to this, I don't have high hopes I'll see anything. Unless I see a an edge, I'm not going to believe it.
--------------------
CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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square_peg
Postmaster
Reged: 03/26/04
Posts: 31402
Loc: Maple Valley, WA
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I think the best we should hope to see is a darkening of the star.
--------------------
Tom (Pegster)
DSH-8 (GSO Dob)
15x70 Oberwerks
SVP/ED80
WO 66 Petzval
Sears Discoverer EQ 60/900
8x42 Regals
History is Philosophy teaching by examples.
Thucydides
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robin_astro
super member
Reged: 12/18/05
Posts: 164
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The AAVSO have now issued a special notice on this event (copied below)
Robin
-----------------------------
AAVSO Alert Notice 393
Monitoring for a planetary transit of HD 80606
February 3, 2009
Dr. Greg Laughlin (Lick Observatory) requests intensive time-series
photometry of the possible transiting extrasolar planetary system HD
80606. This system, recently in the news due to the extreme
temperatures to be found on the planet, is predicted to reach
conjunction on or around HJD 2454876.5 (2009 Feb 14.0 UT), and there is
a low but significant probability (<15%) that the system is eclipsing.
If it eclipses, the duration of the eclipse may be as long as 17 hours.
Observers are requested to perform high-S/N, filtered photometry of this
bright star during a window beginning 48 hours before the predicted
eclipse and ending 48 hours after.
Due to the long duration of the eclipse, it is unlikely that a single
observer will be able to follow the transit from ingress through egress.
Therefore, in order to model the eclipse profile, the data of many
observers will need to be combined. Because the transit is expected to
have low amplitude (on the order of 10 mmag), high-precision photometry
of HD 80606 is required, and users are *strongly encouraged* to fully
calibrate and transform their data and perform an extinction correction
prior to submission. Doing so will make the process of combining data
from different observers far easier. The following color data for HD
80606 should be used when performing transformations to the standard
system: V=9.127 , (B-V)=+0.786 , (V-Rc)=+0.431 , (Rc-Ic)=+0.356 ,
(V-Ic)=+0.784
If you do not transform your data, please make sure you include
photometry of the uneclipsed star either prior to ingress or after
egress, to enable us to detect the eclipse. Without calibration or a
pre- or post-eclipse measure, we cannot compute an offset for your
photometry.
For more information on computing transformation coefficients for your
telescope, please read the following aavso-photometry post by Tim
Crawford from March 2008:
http://www.aavso.org/pipermail/aavso-photometry/2008-March/003382.html
Crawford gives links to two additional papers on CCD coefficients:
http://www.aavso.org/observing/programs/ccd/ccdcoeff.pdf
which is an instruction manual for computing them, prepared by Lou
Cohen, and
http://www.aavso.org/publications/ejaavso/v29n1/35.pdf
which is a paper on the differences between transformed and
untransformed data by Arne Henden. We note that by computing your
transformation coefficients, you can use them both for these data as
well as for all future data you submit to the AAVSO on any star taken
with the same telescope, CCD, and filter set.
Because HD 80606 is bright (V = 9.13), care must be taken when performing
photometry. Please see
http://www.aavso.org/publications/ccdviews/324.shtml#bright
which is a CCD Views article on bright star photometry for suggestions on
how best to perform accurate photometry.
HD 80606 is located at the following (J2000) coordinates:
RA: 09 22 37.5679 , Dec: +50 36 13.397
Charts for HD 80606 may be plotted using VSX:
http://www.aavso.org/observing/charts/vsp/index.html?pickname=HD%2080606
Note that HD 80606 is a close double, and that the star of interest
is the western member of the pair.
Please submit all data to the AAVSO using the name HD 80606 (AUID 000-BCZ-783).
This AAVSO Alert Notice was prepared by Dr. Matthew Templeton.
-------------------------------------------
SUBMIT OBSERVATIONS TO THE AAVSO
Information on submitting observations to the AAVSO may be found at:
http://www.aavso.org/observing/submit/
ALERT NOTICE ARCHIVE AND SUBSCRIPTION INFORMATION
An Alert Notice archive is available at the following URL:
http://www.aavso.org/publications/alerts/
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jgraham
Postmaster
Reged: 12/02/04
Posts: 7033
Loc: Dayton, Ohio
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My guess that in order to see such a slight change your best best is to take lots and lots of data, particularly before and after the event, that way you will have enough baseline data to distinguish between and real brightness changes and random drift in the baseline.
Cool stuff.
--------------------
-John
================================================
Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
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Freddy WILLEMS
Carpal Tunnel
Reged: 11/13/05
Posts: 2901
Loc: Hawaii, Honolulu
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This is already a picture before the event, just want to go with the program ones it happens.
Freddy
--------------------
Freddy
Meade 14" LX200 GPS UHTC GPS on permanent pier
Celestron C 14" Peltier cooled for planetary imaging.
Meade 10" LX200 & TITAN 50:1 mount Gemini 'go to'
Meade 127 mm f/9 APO & TITAN 50:1 mount Gemini 'go to'
W/O 102 mm f/7 APO doublet
Orion 80 mm f/7 ED
DFK 21AU04.AS
ToUcam 840 II pro
Canon 10D Unmoddified
Canon 40D Hutech moddified
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3523
Loc: Doylestown, PA
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You have a start Freddy. I'm curious to know how much fluctuation you have in the magnitude of the comparison, check and target star on a sequence of images. If the difference from image to image (and night to night since this is a rather long transit) is very small you have a good chance of seeing the transit and have your data used.
Go for it and good luck.
--------------------
Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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btieman
professor emeritus
Reged: 07/24/08
Posts: 567
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I spent last night measuring this field to see if I have a shot at seeing anything. I'm thinking not 
I used AASVO HD80606b chart E for reference. This first set is using HD80606a as the comparison and 101 as the check
Time HD80606b HD80606a 101
8:50 8.926 9.1 10.134
9:25 8.918 9.1 10.127
9:39 8.88 9.1 10.055
10:07 8.995 9.1 10.081
10:25 8.969 9.1 10.104
10:40 8.979 9.1 9.974
11:00 8.993 9.1 10.093
11:30 8.972 9.1 10.15
This set uses 96 as the comparison and 101 as the check.
Time HD80606b 96 101
8:50 8.966 9.6 10.169
9:25 8.997 9.6 10.206
9:39 9.021 9.6 10.197
10:07 9.085 9.6 10.171
10:25 9.189 9.6 10.325
10:40 9.185 9.6 10.179
11:00 9.219 9.6 10.318
11:30 9.071 9.6 10.249
All data points are:
CPC1100
F/3.3 FRFF
Orion SSII
V filter
2x2 binning
10x3 stacked
Fresh darks taken at every data point
Flats taken at end of evening
I think I'd need to see a .1 or greater dip to have any sort of confidence of seeing anything--probably greater given the event may be over 2 nights.
I think the camera is most of the problem. I recently got a new SSII in the hopes of automating it through ASCOM--can't find ASCOM drivers for my meade --and I'm having some troubles with the camera.
1) I think it's ABG might be too agressive. I haven't measured the linearity, but I made sure to keep all these exposures with a max count less than half the full range. I think I still see star shadowing that's likely from the ABG.
2) There's a readout issue with the camera that causes corrupt pixels in some frames. I think I was carefull to make sure none of the corrupted pixels were in the aperatures used for measurement, but can't say for sure.
3) As illustrated in the image below, the field wasn't fully flattened by the flat fields--there's still a bit of a "T" shaped darker blotch that I don't yet understand. The flats are working in that some dust motes that I know are on the inside of the CCD window are gone, but he dark area in the middle appears unaffected by the flat corrections???
Orion is sending me a replacement that hopefully will fix some of these issues but it may be that this camera is just not good enough for these sorts of highly sensitive measurements
Brian
--------------------
CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3523
Loc: Doylestown, PA
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It does look like you have a little too much scatter in your data for a reliable measure of the exoplanet transit. But, since this is a rather slow event you may be able to combine (average) the results of several images. Here is a good article from Apogee cameras on CCD test methods including measuring linearity. You really do need to measure your camera's linearity, even if it isn't ABG to know.
--------------------
Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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btieman
professor emeritus
Reged: 07/24/08
Posts: 567
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I'm waiting on a replacement camera. When that arrives, if it resolves some of my other imaging issues, I'll measure the linearity. If it doesn't resolve my problems, well, I'll be back in the market for a new camera with ASCOM drivers.
I found a light leak in my filter changer that appears to account for the funny T pattern in my images. I'm hoping I can take care of that and get another few hours during the week to see if it helps narrow my scatter somewhat.
Brian
--------------------
CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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Freddy WILLEMS
Carpal Tunnel
Reged: 11/13/05
Posts: 2901
Loc: Hawaii, Honolulu
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I don't think we're going to see somethimg.
I hope for the best.
Freddy
--------------------
Freddy
Meade 14" LX200 GPS UHTC GPS on permanent pier
Celestron C 14" Peltier cooled for planetary imaging.
Meade 10" LX200 & TITAN 50:1 mount Gemini 'go to'
Meade 127 mm f/9 APO & TITAN 50:1 mount Gemini 'go to'
W/O 102 mm f/7 APO doublet
Orion 80 mm f/7 ED
DFK 21AU04.AS
ToUcam 840 II pro
Canon 10D Unmoddified
Canon 40D Hutech moddified
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3523
Loc: Doylestown, PA
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Quote:
I don't think we're going to see somethimg.
I hope for the best.
Freddy
I like the saying: "If you don't try you can't succeed."
So even if there may not be a good chance it is worth while trying. At the least you will improve your equipment and technique.
--------------------
Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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btieman
professor emeritus
Reged: 07/24/08
Posts: 567
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Quote:
At the least you will improve your equipment and technique.
This is probably the best reason to try!
Even if there is an ideal crossing, I'm not far enough along in understanding and optimizing my equipment to have a shot at seeing anything. However, because of trying to prepare for this crossing I now have a routine that I can further refine to increase the likely-hood of getting better data. I also know that my filter wheel leaks too much light for high precision photometry.
Old hat for the experienced, I'm sure, but for us Newbies, it's worth the effort because the more useful results are in experience and knowledge--not in the measurements.
Brian
--------------------
CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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btieman
professor emeritus
Reged: 07/24/08
Posts: 567
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Quote:
Time HD80606b HD80606a 101
8:50 8.926 9.1 10.134
9:25 8.918 9.1 10.127
9:39 8.88 9.1 10.055
10:07 8.995 9.1 10.081
10:25 8.969 9.1 10.104
10:40 8.979 9.1 9.974
11:00 8.993 9.1 10.093
11:30 8.972 9.1 10.15
OK, different camera (Meade DSI Pro I) and better attention to detail and I think I'm starting to get there 
HD80606b HD80606a 10.1
9.023 9.1 9.931
9.017 9.1 9.913
9.019 9.1 9.921
9.025 9.1 9.91
9.027 9.1 9.911
9.024 9.1 9.918
9.034 9.1 9.943
9.012 9.1 9.91
9.017 9.1 9.891
9.012 9.1 9.895
9.009 9.1 9.904
9.002 9.1 9.925
9.002 9.1 9.925
9.011 9.1 9.955
9.033 9.1 9.889
9.013 9.1 9.909
9.02 9.1 9.927
9.014 9.1 9.915
9.038 9.1 9.958
9.004 9.1 9.862
8.999 9.1 9.885
9.032 9.1 9.885
9.025 9.1 9.867
9.046 9.1 9.868
The span of data for HD80606b for the first try was 0.115 and for the 10.1 reference star it was 0.160. For the most recent try the span for HD80606b is 0.047 and for the 10.1 reference it is 0.096. Both data sets were taken over ~2 hours.
My flat corrected images still don't look as flat as they should. Since I'm on an alt/az mount, I can see the stars drift through light/dark patches as the field rotates. I think this is why the HD80606a/HD80606b has a smaller scatter than the HD80606a/101 comparisons. I see an even larger scatter if I choose comparison stars even farther apart--it's a good thing I've got a wedge on order
At least I seem to be moving in the right direction!
Brian
--------------------
CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3523
Loc: Doylestown, PA
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That data looks very good Brain.
I loaded your data into Excel and plotted each. The first column has an upward trend and the third has a downward tend. This very well could be caused by color dependent atmospheric extinction as the thickness of the atmosphere changed during tracking. HD80606a and the 9.1 star have a (V-Rc)=+0.43 whereas the 10.1 star has a (V-Rc)=+0.639. The 10.1 star is redder and will dim or brighten differently than the 9.1 as it goes from zenith to toward the horizon.
I think you are also ready to use the precise photometry data for the comparison stars.
Goto the AAVSO chart plotter and use star name "HD 80606" then check the 'Field Photometry' box. This will give a list of the comp stars and their photometry with different filters.
I'm thinking you may now have a chance to see the transit (at least your data in combination with others data). I suggest you keep all of the data and contact the AAVSO to obtain help in determining your extinction corrections (I have not done this and only know the basic theory on how).
Definitely going in the right direction. Please keep us posted with your results.
--------------------
Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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btieman
professor emeritus
Reged: 07/24/08
Posts: 567
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Doh! That's why everyone says adjust for atmospheric extinction!
Now I have a new question I took my data with a V filter. Do I still need to adjust for extinction? The extinction in V for both stars should be the same within a given frame.
I still saw some background pattern in my corrected images--especially around the amplifier glow and I had some vignetting that didn't fully flat out (I had put the wrong spacer in  ) I'm currently in alt/az so the stars drifted through these apparently non-flat regions during the night. I think if I were equitorial so the stars would stay in the same region of the chip the scatter would be a bit smaller still.
Tonight looks cloudy with a chance of meatballs (sorry--kid book reference there ) Tomorrow looks clear. I hope to set up and just star at HD80606 all night and hope Sunday will be OK as well...and we'll see what we shall see
Thanks for all the encouragement Walt!
--------------------
CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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jgraham
Postmaster
Reged: 12/02/04
Posts: 7033
Loc: Dayton, Ohio
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If I understand how differential photometry works when your variable and calibration stars are in the same frame atmospheric extinction shouldn't be a problem as long as you calibrate internally for each frame. Also, aperture photometry is supposed to correct for the background sky enegry for each measurement, so a smooth gradient shouldn't cause a problem, though a sharp gradient like a dust donut might be another issue. However, I haven't tried cutting it that fine yet and keeping my measurements to 0.1 magnitude. I'll start exploring pushing that to 0.01 magnitude once I gain some experience.
If we ever get some steady clear weather I might try leaving my scope outside for a couple of hours taking some long sequences. That would give me some data to work with to see how this stuff really works. It's beautiful right now, but it's a trap; we're supposed to get rains and snow tonight. Fortunately, I've got a stack of images from last night to go over.
Really neat stuff.
--------------------
-John
================================================
Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
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