TrES-3

 

TrES-3 is an extrasolar planet orbiting the star GSC 03089-00929. It has an orbital period of just 31 hours and is undergoing orbital decay due to tidal effects. It is a very massive planet, nearly twice the mass of Jupiter. It is the third transiting planet found by the Trans-Atlantic Exoplanet Survey. It was discovered in the constellation Hercules about 10 degrees west of Vega, the brightest star in the summer skies. The planet's home star is slightly smaller and cooler than the Sun. The 'year' is less than one and a third days, one of the shortest known (from wikipedia). TrES-3 is 1300 ± 600 light years from Earth. The star, GSC 03089-00929, is spectral type G, the same as our own sun. This planet was discovered in May, 2007.

These light curves were collected on 7/7/2008 from my backyard observatory as the planet passed in front of it's parent star, dimming the light from that star by 2.98% (or 0.03 magnitudes). Integrations were 5 minutes (no binning), and a photometric V filter was used. This combination yielded an estimated signal to noise ratio of 725.7 for the target star.

This plot shows differential photometry of TrES-3 vs. an averaged ensemble of 5 nearby stars. All of the stars in the ensemble are dimmer than the target star. The hump on the right is suspected to be the result of an overall trending up (brightening) of the target star vs. the ensemble due to differential extinction or some other systematic. Next thing to try is to include only ensemble stars that are close to the target star in temp/color.

 

 

This plot shows differential photometry of one of the ensemble stars vs. the rest of the ensemble.

 

 

Sky conditions were good until about mid-transit when the haze/fog started rolling in and sky levels doubled. This probably explains the increasing uncertainty in the target and ensemble stars towards the end of the observation.

 

 

This plot shows the airmass over the time period of the transit. The increasing airmass correlates with the increasing sky level and increasing noise.

 

Field of view (700x500, cropped from the center of the 2184x1472 images) showing TrES-3 and the 5 ensemble stars used for differential photometry. Using ensemble stars farther away resulted in more systematic errors over time.

 

 

The raw data (from AIP4WIN):


AIP4Win Multiple-Image Photometry Tool
Differential (w/ Extra Decimals) Photometry Report
AIP4Win v.,2.1.8
Filename of first image: ,tres3-005V.FIT
Number of files selected: ,34
Star aperture radius: ,6
Sky annulus inner radius: ,9
Sky annulus outer radius: ,15
Star aperture pixels: ,115
Sky annulus pixels: ,274
Zero point: ,25.0
Integration time: ,300.0
Gain [e/ADU]: ,1.33
Readout noise [e rms]: ,15.0
Dark current [e/sec/pix]: ,5.0
Time of observation:
Date, time, exposure from ,FITS header
First Image Date: ,2008-07-07
First Image Time: ,05:55:35
First Exposure Time: ,300 seconds
Filter: ,PhV
Clock time zone: ,0 hours
Offset (true-clock): ,0 seconds
Heliocentric correction: ,0 seconds
Julian Day (midexposure): ImageTime + (Exposure / 2)
First Mid-exposure Date: ,2008-07-07
First Mid-exposure Time: ,05:58:05.000
First Image Stars
Star, Star_X, Star_Y, Max_PV, Sky_ADU, Star_ADU, Mag,±Sigma
Var, 382.384, 269.261, 29693.0, 667.248, 503861., 16.937,0.0015
C1, 336.480, 314.461, 7354.0, 648.509, 121803.5, 18.479,0.0039
C2, 196.975, 307.882, 7122.0, 647.993, 112171.8, 18.568,0.0041
C3, 169.135, 231.557, 5813.0, 649.882, 90262.3, 18.804,0.0049
C4, 329.158, 142.163, 17210.0, 658.783, 279444., 17.577,0.0022
C5, 555.500, 62.178, 13371.0, 657.732, 222850., 17.823,0.0025
Ens, , , , , 826531., 16.400,0.0014
-------------------------------------------------------------------
   Seq_#,YYYY-MM-DD,HH:MM:SS.sss, Julian_Day, (V-C1),±Sigma, (C2-C1),±Sigma,    (V-Ens),±Sigma, Sky_ADU,File_Name
   00001,2008-07-07,05:58:05.000,54654.7486690, -1.5416,0.0042, 0.0894,0.0057,    0.5374,0.0020, 667.248,tres3-005V.FIT
   00002,2008-07-07,06:03:56.000,54654.7527315, -1.5355,0.0041, 0.0879,0.0056,    0.5392,0.0020, 647.938,tres3-006V.FIT
   00003,2008-07-07,06:09:49.000,54654.7568171, -1.5412,0.0041, 0.0885,0.0056,    0.5356,0.0020, 646.663,tres3-007V.FIT
   00004,2008-07-07,06:15:41.000,54654.7608912, -1.5411,0.0041, 0.0924,0.0056,    0.5365,0.0020, 641.211,tres3-008V.FIT
   00005,2008-07-07,06:21:36.000,54654.7650000, -1.5410,0.0041, 0.0893,0.0056,    0.5386,0.0020, 643.1,tres3-009V.FIT
   00006,2008-07-07,06:27:27.000,54654.7690625, -1.5424,0.0041, 0.0884,0.0056,    0.5395,0.0020, 633.823,tres3-010V.FIT
   00007,2008-07-07,06:33:17.000,54654.7731134, -1.5253,0.0041, 0.1049,0.0055,    0.5425,0.0020, 640.925,tres3-011V.FIT
   00008,2008-07-07,06:39:08.000,54654.7771759, -1.5351,0.0040, 0.0991,0.0055,    0.5413,0.0020, 627.237,tres3-012V.FIT
   00009,2008-07-07,06:44:58.000,54654.7812269, -1.5377,0.0040, 0.0900,0.0055,    0.5423,0.0020, 631.88,tres3-013V.FIT
   00010,2008-07-07,06:50:49.000,54654.7852894, -1.5333,0.0041, 0.0968,0.0055,    0.5391,0.0020, 624.83,tres3-014V.FIT
   00011,2008-07-07,06:56:40.000,54654.7893518, -1.5342,0.0041, 0.0938,0.0055,    0.5388,0.0020, 629.963,tres3-015V.FIT
   00012,2008-07-07,07:02:30.000,54654.7934028, -1.5389,0.0041, 0.0892,0.0055,    0.5405,0.0020, 630.375,tres3-016V.FIT
   00013,2008-07-07,07:08:21.000,54654.7974653, -1.5332,0.0041, 0.0968,0.0056,    0.5386,0.0020, 642.967,tres3-017V.FIT
   00014,2008-07-07,07:20:03.000,54654.8055903, -1.5367,0.0041, 0.0904,0.0056,    0.5470,0.0020, 646.901,tres3-019V.FIT
   00015,2008-07-07,07:25:53.000,54654.8096412, -1.5292,0.0041, 0.0874,0.0056,    0.5502,0.0020, 648.022,tres3-020V.FIT
   00016,2008-07-07,07:31:43.000,54654.8136921, -1.5196,0.0042, 0.0950,0.0057,    0.5532,0.0021, 660.295,tres3-021V.FIT
   00017,2008-07-07,07:37:34.000,54654.8177546, -1.5227,0.0042, 0.0872,0.0058,    0.5597,0.0021, 680.333,tres3-022V.FIT
   00018,2008-07-07,07:43:25.000,54654.8218171, -1.5146,0.0042, 0.0968,0.0058,    0.5574,0.0021, 683.996,tres3-023V.FIT
   00019,2008-07-07,07:49:15.000,54654.8258681, -1.5221,0.0043, 0.0813,0.0058,    0.5578,0.0021, 695.261,tres3-024V.FIT
   00020,2008-07-07,07:55:06.000,54654.8299306, -1.5127,0.0043, 0.0990,0.0059,    0.5633,0.0021, 715.474,tres3-025V.FIT
   00021,2008-07-07,08:00:56.000,54654.8339815, -1.5166,0.0044, 0.0901,0.0060,    0.5680,0.0021, 728.219,tres3-026V.FIT
   00022,2008-07-07,08:06:48.000,54654.8380556, -1.5188,0.0043, 0.0945,0.0059,    0.5547,0.0021, 729.354,tres3-027V.FIT
   00023,2008-07-07,08:12:38.000,54654.8421065, -1.5231,0.0044, 0.0888,0.0059,    0.5518,0.0021, 732.369,tres3-028V.FIT
   00024,2008-07-07,08:24:20.000,54654.8502315, -1.5390,0.0047, 0.0850,0.0064,    0.5370,0.0022, 784.413,tres3-030V.FIT
   00025,2008-07-07,08:30:10.000,54654.8542824, -1.5447,0.0048, 0.0856,0.0066,    0.5324,0.0023, 844.167,tres3-031V.FIT
   00026,2008-07-07,08:36:00.000,54654.8583333, -1.5374,0.0049, 0.1052,0.0068,    0.5228,0.0024, 886.721,tres3-032V.FIT
   00027,2008-07-07,08:41:51.000,54654.8623958, -1.5502,0.0048, 0.0917,0.0067,    0.5301,0.0023, 921.712,tres3-033V.FIT
   00028,2008-07-07,08:47:42.000,54654.8664583, -1.5460,0.0049, 0.0856,0.0068,    0.5299,0.0023, 945.274,tres3-034V.FIT
   00029,2008-07-07,08:53:33.000,54654.8705208, -1.5403,0.0049, 0.0996,0.0068,    0.5312,0.0023, 970.118,tres3-035V.FIT
   00030,2008-07-07,08:59:23.000,54654.8745718, -1.5443,0.0051, 0.0988,0.0070,    0.5254,0.0024, 1010.853,tres3-036V.FIT
   00031,2008-07-07,09:05:14.000,54654.8786343, -1.5525,0.0054, 0.0838,0.0075,    0.5297,0.0025, 1104.577,tres3-037V.FIT
   00032,2008-07-07,09:11:05.000,54654.8826968, -1.5424,0.0057, 0.1034,0.0080,    0.5270,0.0026, 1192.519,tres3-038V.FIT
   00033,2008-07-07,09:16:56.000,54654.8867593, -1.5468,0.0057, 0.0880,0.0080,    0.5278,0.0026, 1257.131,tres3-039V.FIT
   00034,2008-07-07,09:22:47.000,54654.8908218, -1.5384,0.0059, 0.0915,0.0083,    0.5286,0.0027, 1373.302,tres3-040V.FIT
 
Image data (from CCDInspector):

Image File FWHM Aspect (%) Background (adu) Altitude Air Mass Date & Time Temperature
tres3-005V.FIT 2.41" 11 7092 +79º 26' 27" 1.02 07/06/08 22:55:35 -20.0
tres3-006V.FIT 2.27" 9 7341 +80º 02' 12" 1.02 07/06/08 23:01:26 -20.0
tres3-007V.FIT 2.13" 5 5800 +81º 18' 15" 1.01 07/06/08 23:07:19 -20.0
tres3-008V.FIT 2.23" 7 6124 +82º 35' 00" 1.01 07/06/08 23:13:11 -20.0
tres3-009V.FIT 2.23" 14 6647 +83º 51' 06" 1.01 07/06/08 23:19:06 -20.4
tres3-010V.FIT 2.37" 16 6255 +85º 07' 12" 1.00 07/06/08 23:24:57 -20.0
tres3-011V.FIT 2.41" 8 6984 +86º 23' 14" 1.00 07/06/08 23:30:47 -20.0
tres3-012V.FIT 2.39" 9 7717 +87º 38' 26" 1.00 07/06/08 23:36:38 -20.4
tres3-013V.FIT 2.34" 8 5998 +88º 13' 02" 1.00 07/06/08 23:42:28 -20.0
tres3-014V.FIT 2.39" 6 6478 +89º 25' 23" 1.00 07/06/08 23:48:19 -20.0
tres3-015V.FIT 2.28" 4 5730 +89º 43' 27" 1.00 07/06/08 23:54:10 -20.0
tres3-016V.FIT 2.31" 8 6303 +88º 33' 03" 1.00 07/07/08 00:00:00 -20.4
tres3-017V.FIT 2.45" 12 7359 +87º 18' 08" 1.00 07/07/08 00:05:51 -20.4
tres3-019V.FIT 2.28" 9 6135 +85º 27' 08" 1.00 07/07/08 00:17:33 -20.0
tres3-020V.FIT 2.33" 9 6614 +84º 12' 11" 1.01 07/07/08 00:23:23 -20.4
tres3-021V.FIT 2.80" 16 9524 +82º 56' 20" 1.01 07/07/08 00:29:13 -20.0
tres3-022V.FIT 2.59" 16 8601 +81º 40' 26" 1.01 07/07/08 00:35:04 -20.4
tres3-023V.FIT 2.76" 15 9018 +80º 25' 14" 1.01 07/07/08 00:40:55 -20.4
tres3-024V.FIT 2.93" 11 8334 +79º 09' 12" 1.02 07/07/08 00:46:45 -20.0
tres3-025V.FIT 2.93" 10 11510 +78º 34' 02" 1.02 07/07/08 00:52:36 -20.4
tres3-026V.FIT 2.65" 9 9768 +77º 18' 05" 1.03 07/07/08 00:58:26 -20.4
tres3-027V.FIT 2.53" 6 7723 +76º 03' 18" 1.03 07/07/08 01:04:18 -20.4
tres3-028V.FIT 2.75" 15 10655 +74º 47' 21" 1.04 07/07/08 01:10:08 -20.0
tres3-030V.FIT 3.42" 7 18621 +72º 17' 14" 1.05 07/07/08 01:21:50 -20.0
tres3-031V.FIT 3.37" 6 13844 +71º 02' 24" 1.06 07/07/08 01:27:40 -20.4
tres3-032V.FIT 3.45" 15 16565 +70º 27' 03" 1.06 07/07/08 01:33:30 -20.4
tres3-033V.FIT 3.01" 7 14906 +69º 13' 24" 1.07 07/07/08 01:39:21 -20.4
tres3-034V.FIT 2.90" 9 11223 +67º 58' 02" 1.08 07/07/08 01:45:12 -20.4
tres3-035V.FIT 2.80" 8 10347 +66º 44' 11" 1.09 07/07/08 01:51:03 -20.0
tres3-036V.FIT 3.04" 11 13737 +65º 29' 15" 1.10 07/07/08 01:56:53 -20.0
tres3-037V.FIT 3.18" 13 14249 +64º 15' 12" 1.11 07/07/08 02:02:44 -20.0
tres3-038V.FIT 3.20" 10 15393 +63º 01' 08" 1.12 07/07/08 02:08:35 -20.0
tres3-039V.FIT 2.90" 8 12956 +62º 27' 12" 1.13 07/07/08 02:14:26 -20.4
tres3-040V.FIT 2.79" 13 11505 +61º 14' 02" 1.14 07/07/08 02:20:17 -20.4