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Observations of GLAST AGN Targetswith the Spitzer Space Telescope and Ground Based Observatories |
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UPDATE- May 2005The second Spitzer observation has been scheduled during a time which is impossible for ground based observers to see the target as it is daylight. However, we can still do our work if you make observations before and after the Spitzer observation. We recommend after astronomical twilight on the day before and the day after. Also, recent recommendations by our scientist advisors suggest the best filters to use are V,R,I from a standard UVBRI set. If all you have are LRGB filters, we're interested in L and R for related student projects. We're interested in L data on any observation at any time for time-based observations. We also need your images to be calibrated with darks and flats as necessary to reduce noise and make the pictures photometrically useful. IMPORTANT: we will take every image you take whether or not they are calibrated and whether or not they are filtered, because we may be able to work with them for purposes our student investigators have yet to invent. In other news, the IRAC observation will occur on (Please note the correction from the mailing list time of 11:32 PM...) Good luck everyone! We'll be in touch next week with everyone on the mailing list about transmitting your data to us. Observing FAQ1. What are the coordinates of 4C 29.45?
Information about GTN 7 from the GTN Program web site.2. Where can I get a finder chart? Go this page http://gtn.sonoma.edu/participants/catalog/ and click on the button for GTN 7. Finder charts and magnitudes of calibration stars are posted. On the home page for this project you can see a sample picture and a low-rez finder chart. 3. How long an exposure do I need? We have used a 1 to 2 minute exposure on a CCD camera attached to a 14" telescope and gotten useful data. Longer exposures may be needed for filtered observations. If you can see it in the image, we can probably use it. 4. Where do I send the files? You can send the files to me, Jeff Adkins, at astronomyteacher"at"mac.com. If you have many megabytes of data you can either send me a CD or arrange to upload them to my public .Mac folder (should work for Mac and PC). Contact me for details. 5. What format should the files be in? 16 bit unsigned FITS is best for us, although we can read 16 bit signed if necessary. JPG, GIF, BMP, etc, and other common file formats do not contain the astronomical data we require. 6. Do you need our longitude and latitude? No, since we are doing differential photometry compared to nearby standards, we do not need to know the airmass or other details that depend on your position. We do need to know the date and time of the observation, plus your time zone if you do not report the time in UT. 7. What is a "calibrated image?" Explaining how to make a calibrated image is beyond the scope of this site. The images need to have had dark, flat, and bias frames applied so they are photometrically useful. This essentially reduces noise from the image due to sky brightness, instrumental signals which do not correspond to light, and heat in the camea. Your camera manual should explain how to do this.
Non_IR blocked clear, I think, but I am double-checking on this. We have calibration
stars for U,V,B,R, and I. Therefore all are useful. You'll note some
of the magnitudes get down as far as 17 in U, so getting those will
be more challenging than in the other bands. The finder charts and
calibration data is on the GTN program web site (see link at left,
click on #7.) (Binning is a way of combining pixels when offloading the image from the chip so that fewer numbers are needed, speeding image download time and reducing file size.) Since we are not interested in position data, the target is starlike and not extended and the resolution of the target serves only to identify it, I would say it does not matter. Some of the stars we use to positively identify the target on the finder chart are even dimmer than it is, and might be lost in coarse binning. If you can positively identify it off of the finder, I would say not. 11. When should I take pictures? Before, during and after the Spitzer observation. There will be two
Spitzer observations of our target. The first one has been scheduled
for May 14 2005, 10:40:36.400 UT, which is Any observations you make before or after will be used to track change over time to make sure the target is not intrinsically changing. If it is experiencing a burst, we will hopefully be able to adjust our observations using the time-based data. 12. What size in arcminutes should the image be? The finder chart is 10 x 10 arcmin. If yours is larger that's OK. If smaller, there may not be any standard stars in the image. You have only two options in that case. Move the telescope to the standards and take an identical exposure, or use the standards to find the magnitudes of stars closer to the target. 13. How do we reduce the data to a light curve?
Additional information will be added to this site as the project progresses.
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