Generating Light Curves - APT and Excel

Mysterious IRAC images, along with a chart indicating 3 stars for which you should perform photometry. Construct light curves by plotting your photometry as a function of time (found in the image headers)

[1] Click here or paste this into browser ftp://anon-ftp.ipac.caltech.edu/outgoing/hoard/nitarp/test_lightcurve_data.tar.gz

Sample IRAC images from each channel for HAT-P-1b, TrES-2, and TrES-4 [2] Click here or paste this into browser ftp://anon-ftp.ipac.caltech.edu/outgoing/hoard/nitarp/sample_images.tar.gz

A note on IRAC image file names: Here's a sample image name...

SPITZER_I1_24745472_0002_0000_4_bcd.fits

This follows a general file naming convention, as follows:

"SPITZER" = in case you forgot which satellite you were using

"I1" = Instrument (I for IRAC) and channel number. In this case, channel 1 = 3.6 microns. Other channel possibilities include 2 = 4.5 microns, 3 = 5.8 microns, 4 = 8 microns. Note that, as described in the IRAC Data Handbook and the document on performing IRAC photometry that I circulated amongst you a while ago, these channel wavelengths are not the "true" (or isophotal) values that should be used during data analysis. The isophotal values are channel 1 = 3.544 microns, 2 = 4.479, 3 = 5.710, 4 = 7.844.

"24745472" = Unique AOR identifier for this observation (not for this IMAGE, but for all images comprising a single Spitzer visit to the target).

"0002" = Image sequence number in this observation; in this case, the second image of the sequence.

"0000" = Some observing modes obtain more than one exposure per "image". In such cases, this sequence number would increment upwards.

"4" = number of times this image has been reprocessed through successive (improved) versions of the data processing and calibration pipeline. All of the data I have sent to you (indeed, all of the IRAC data now available in the Spitzer archive) have been processed with the latest and greatest version of the pipeline, S18.7.0.

"bcd" = Basic Calibrated Data. The standard result from raw Spitzer data that have been run through the processing and calibration pipeline. This is the data product that we work with.

".fits" = It's a standard FITS image, can be loaded into DS9. The BCD images are flux calibrated in units of surface brightness per pixel, MJy/sr (mega-Jansky per steradian). The also include world coordinate solutions in their image headers, so can be displayed in the usual format (N up, E to the left) and have, for example, 2MASS catalogs overlaid on them, etc.