Knowledgebase: Spitzer: General

Spitzer Documentation

All the Spitzer documentation can be found linked from here.

Spitzer Canonical Papers

All the Canonical papers can be found linked from here. Note that large projects (Legacy, GTO, Exploration Science) may have their own canonical paper to cite if you use their data. See the projects linked from here.

How should I reference my Spitzer data in my journal articles? What acknowledgment should I use?

Two pages with the answers are Guidelines for Publication Acknowledgments and How to reference a Dataset ID in your journal articles.

Where was Spitzer EXACTLY during my observations so that I can calculate light-time corrections?

This information is in the fits headers for data processed with pipelines > S16. Here is a sample snippet:

SPTZR_X =       6084048.364647 / Heliocentric J2000 x position (km)
SPTZR_Y =    -138993559.088106 / Heliocentric J2000 y position (km)
SPTZR_Z =     -62551818.282086 / Heliocentric J2000 z position (km)
SPTZR_VX=            29.396946 / Heliocentric J2000 x velocity (km/s)
SPTZR_VY=             0.639668 / Heliocentric J2000 y velocity (km/s)
SPTZR_VZ=             0.729644 / Heliocentric J2000 z velocity (km/s)
SPTZR_LT=           508.824176 / One-way light time to Sun's center (s)
SCLK_OBS=        837186592.637 / SCLK (~sec. since 1/1/1980) at ramp start.
ET_OBS  =        205991150.144 / Ephemeris time (seconds past J2000 epoch)
DATE_OBS= '2006-07-12T15:44:44.960' / UTC date & time at ramp start.
MJD_OBS =        53928.6560759 / Mod. Julian Date (UTC) (days) at ramp start.
HMJD_OBS=        53928.6558680 / Corresponding Heliocen. Mod. Julian Date
UTCS_OBS=        205991084.960 / UTC seconds past year 2000 at ramp start.
The inertial reference frame for the calculations is ICRF, with its origin at the Sun's center. The target used for computing helocentric Julian data is specified by RA_RQST and DEC_RQST in the FITS header. Note that since the range of the target is unavailable, it is impossible to include a correction for the target's Spitzer/Sun parallax. If you'd like to calculate this information yourself, please see this file.

I've read all of the documentation, the FAQ pages and checked the bug list, and I still can't find the answer to my question. How do I get help?

If you are having problems with MOPEX/APEX, Bandmerge, SPICE, CUBISM, IRSCLEAN, IRSFRINGE, or the GeRT then please submit a ticket to the IRSA Helpdesk and we'll be happy to help. If you are having problems with Contributed Software then please contact the appropriate distributor.

Where should a typical observer start their analysis?

If you were asking for pointers to documentation, this page is one-stop-shopping for investigators looking to get started working on Spitzer data -- archive access, data handbooks, software, data processing examples, even IAU naming guidelines and acknowledgments.

If you were asking which data files to start with, in general, most observers will want to (and feel confident in) starting their analysis with the Basic Calibrated Data (BCD) processed by the Spitzer Science Center and available for download from the Spitzer Heritage Archive.

What instruments were available in Cycles 6, 7, 8, 9, 10, 11, 12, 13, 14?

Cycles 6 and up took place during the Spitzer 'warm' mission after the cryogenic mission ended. After cryogen depletion, the observatory continued operating using only the 3.6 and 4.5 micron channels on the IRAC instrument. The longer wavelength IRAC channels (5.6 and 8.0 microns) and the MIPS and IRS instruments were unavailable.

What is your image use policy?

You are free to reprint any image on our website without any specific permission required. For more information, and for information on how to attribute credit, please see our image use policy at