TrES-1 "b" Results:
UPDATE: Ron Bissinger has completed a bootstrap Monte-Carlo analysis of multiple TrES-1 light curves. His analysis suggests that the pre-ingress and post-egress features that have been noted in many of the TrES-1 light curves may have statistical significance. Bissinger's report is HERE.
Background: The transiting planet orbiting TrES-1 was discovered using a distributed network of telescopes. TrES-1 "b" is the first planet to be detected around a bright parent star using the transit method (as opposed to HD 209458 "b", which was discovered first with the Doppler radial velocity method, and then observed to transit as a result of detailed photometric follow-up. The discovery of TRES-1 "b" is described in a preprint by Alonso et al. (2004) of an article accepted by Astrophysical Journal Letters. Our ephemeris calculations are based on the orbital elements reported by Alonso et al.
The planet is very similar in mass to HD 209458 "b" (Alonso et al place the mass at 0.75 +/-0.07 Jupiter Masses.) The parent star is a V=11.79 magnitude K0 V type star. TrES-1 "b" represents a good target for transitsearch.org observers who want to demonstrate their observing technique using a known transiting planet. Located in the constellation Lyra, TrES-1 is an excellent late-Summer target for observers in the Northern Hemisphere. The transit depth is observed to be ~2%.
Transitsearch observer Ron Bissinger is obtaining baseline photometry of the field of view, and will observe transits with a 14''/ST-10 combination starting with the Sept. 16th, 2004 opportunity. The parent star is surrounded by many good comparison stars of similar magnitude (V=11-12), so differential photometry should be straightforward in this case. Ron can be reached at RBissinger at aol dot com.
On August 29, 2004,
Bissinger reports:
"Spent the last couple of nights getting baseline photometry on TrES-1b. Fairly straightforward... I used a 14'' SCT with an ST-10XME @f.5.5 with a red filter and 70 second exposures. Thre's a good Vr=11.2 mag comp star just 45 arc-seconds away (GSC 2652:152) so any scope/CCD combination will get both in the field. Here is a plot of my results so far. Will have to wait until September 16th to see the transit. (in Northern California)
On September 1, 2004,
Transitsearch observer Tonny Vanmunster of the CBA Belgium Observatory reports:
From Tonny Vanmunster at cbabelgium dot com Wed Sep 1 15:38:26 2004
Date: Thu, 2 Sep 2004 00:16:10 +0200
From: Tonny Vanmunster
Subject: TrES-1 transit observation started at CBA Belgium Observatory - ingress successfuly measured
I have pleasure to inform you that I started a time-series photometry session on a TrES-1 transit earlier tonight (2004 Sep 1, at 19h34m UT), under very good sky conditions. I'm using a 0.35-m f/6.3 telescope with an unfiltered ST-7XME CCD camera, at CBA Belgium Observatory. An intermediate light curve analysis of the acquired data (up till 22h10m UT) very well shows the ingress, which seems to have started very close to the predicted time of 21h13m UT. A fading by approx. 0.02 mag is clearly visible in the "raw" light curve (that is, even without stacking and/or averaging images).
I will continue to measure the transit all night long - given the very good weather conditions, and spend time tomorrow in the final analysis of the results. I will keep you informed about the outcome and will present results on my website as well.
Best regards, Tonny
At JD 2453250.462, (2004, Sept. 1, 23:05:52 UT) Tonny sends an in progress light curve:
From Tonny Vanmunster at cbabelgium dot com Wed Sep 1 16:13:48 2004
Date: Thu, 2 Sep 2004 01:01:45 +0200
[Attached] is a "real-time" update : tonight's light curve (up to Sep 1.935 UT) showing the ingress in full detail. I have simply averaged each 3 data points in the raw light curve, to obtain the one in annex. More (including the full light curve) to follow later tomorrow ...
Best regards, Tonny
Vanmunster's final reduced light curve is shown at the top of the page.
Also, on September 1, Samo Smrke and Nicolaj Stritof of Slovenia observed the transit (as reported by the Extrasolar Planets Encyclopedia). Their light curve and figure caption + photometric data also show an extremely well-resolved transit.
On Sept. 5, 2004:
Vanmunster reports a second succesful transit observation. The light curve is shown below, with details at www.cbabelgium.com:
Also on Sept. 4th, the transit was observed by Ondrej Pejcha. He reports that his observations were obtained using a 0.4m telescope of the N. Copernicus Observatory and Planetarium in Brno, Czech Republic with an SBIG ST-7 attached. This setup gives 13x9 sq. arc min FOV with a scale of 2.2 arcsec/pixel. The exposure times were 45s for most of the evening, but in the end, the exposures were lengthened to 60 s to compensate for high airmass and a nearby tree. The aperture photometry was done using Munipack, which is based on DAOPHOT II. The points on the graph are averages of 5 subsequent images and the error bars are rms.
A third observation of the September 04 transit was obtained by Pertti Paakkonen, who reports that because of weather, he was able to observe only up until shortly before the egress began. Nevertheless (as shown below) his data is also very good. The light curve and observational details are at http://cc.joensuu.fi/seulaset/ccd/20040904/.
On September 8, 2004, as the optimal observing longitudes shift toward western Europe, Robin Leadbeater in the UK reports a succesful observation using a webcam. He writes:
"I have been following recent amateur observations of this object with interest and attempted my own measurements with a modified webcam during the transit on the 7th of September. (This is my first serious attempt at photometry, but it was an opportunity too good to miss!) The light curve is posted at: http://mysite.wanadoo-members.co.uk/astro2/TrES_1.htm.
On Sept. 23, 2004 Bruce Gary, of Hereford, Arizona, caught the transit in the United States. His light curve is shown below:
Sept. 26th, 2004, Joe Garlitz, located in Northeast Oregon, USA, reports a succesful observation of the transit on the night of the 25th/26th. His light curve is shown below: Further details at: http://www.oregonvos.net/~jgarlitz.
On Sep. 28, 2004, Ron Bissinger, of Pleasanton, California, observed the transit on the night of the 28th/29th. His light curve is shown below:
Nov. 27, 2004: Arto Oksanen, of Nyrola Observatory in Finland (whose observations of the HD 209458 b transit were an inspiration for transitsearch.org) reports a successful TrES-1 observing run that netted a full transit. His preliminary photometry, obtained with AIP4Win using a single comparison star is located here , with a description here, at the Nyrola Observatory web site. Oksanen made the observations with a 16-inch Meade LX200 and an SBIG ST8XE with a V filter. His more detailed analysis (done with IRAF) yields the following light curve:
Dec. 18, 2004, Geir Klingenberg of Norway reports a successful observation of the full Nov. 28, 2004 TrES-1 transit. His light curve is shown below, with technical details and information about his observatory located at this web address. His figure shows the average differential magnitude between the TrES-1 host star and four comparison stars. Each data point is an average of two subsequent 75 sec unfiltered exposures which were calibrated and reduced using AIP4Win. The check star light curve is also shown, and has a standard deviation of 0.0047.
Notes for observers:
TrES-1 has the following properties (taken from Alonso et al 2004):
RA=19:04:09.8 (J2000); Dec = +36:37:57 (J2000)
R=11.34; V=11.79; B-V=0.78
Names: GSC 02652-01324; 2MASS 19040985+3637574
![[Attached] is a "real-time" update](TrES1_vanmunster1.jpg){kind=link}
