"Stellar Distributions in Dark Matter Halos: Looking Over the Edge" is an accepted Spitzer Science proposal that will investigate the outer structures of a large sample of nearby galaxies. Large IRAC 3.6 and 4.5 um maps of 92 galaxies will be taken at unprecedented depth in order to understand how outer and inner structures of galaxies interact. This website will provide details of the data processing for the IRAC imagery.

The Sample Summary Table

Surface Brightness Profiles

Tarball (Everything, last updated Dec. 20 2013)

Also available at arapaho:/arapaho4/shawns/EDGES/final/dec2013_release/

Surface Brightness Images

Data Processing


Astronomical Observation Requests (AORs) inform the Spitzer science staff when and where to point the telescope. We must be careful in making these in order to avoid bright stars and lineup edge-on galaxies so we can make the best use of the telescope's time. Below are links to two tables containing pointing maps for all the galaxies in our sample. (warning: the table with images may take a long time to load)

Table with Images

 Table without Images

Stellar Avoidance

Bright stars in our AORs can saturate and ruin an image. Also, IRAC has the nasty habit of leaving ghost images after viewing a very bright star so these stars should be avoided if possible. To determine if a star will be a problem we look at the star's K-band magnitude from the 2MASS catalog. Suspect stars are found by examining the AORs and comparing them to known problem stars. Also, from the LVL survey we have images of a K_m=7 mag (UGC07916) star and a K_m=7.6 mag (CGCG217018) star. LVL had a much shorter exposure time than EDGES so stars of this magnitude or brighter will be a problem. Also, from our pilot survey UGC1281 has a 6th and 4th magnitude star. The effect of these stars on the irac1 map is shown below.

UGC07916 CGCG217018

In the EDGES sample, we know that there is a 6.1 mag star in the NGC4460 field and a 6.9 mag star in the NGC4203 field. Any star inside an AOR that looks brighter than those two stars could be a problem. Below is a table summarizing stars that have been found so far in the AORs.

Galaxy K_m (mag) Distance (arcmin) Cliff's Criterion The Solution
NGC3507_01 6.69900 10.2934   Offset NoTiming IRAC1 IRAC2
NGC3726 6.83500 14.7452   Offset ExistingTiming IRAC1 IRAC2
NGC3893 3.85400 12.6747   Offset Timing IRAC1 IRAC2 MODIRAC1 MODIRAC2
UGC06112 5.81800 9.08095 FLAGGED! Offset Timing IRAC1 IRAC2
NGC3917 6.46400 18.1011   Offset ExistingTiming IRAC1 IRAC2
NGC3922 6.90200 11.6625   Offset Timing IRAC1 IRAC2
NGC3938 6.84400 10.1343   Offset ExistingTiming IRAC1 IRAC2
UGC06917 6.63800 11.8048   Offset NoTiming IRAC1 IRAC2
UGC06983 3.62300 17.3295   NoOffset NoTiming N/A N/A
NGC4051 6.05200 16.6320   NoOffset NoTiming BetweenStars N/A
NGC4085_4088 6.30100 13.3117   Offset Timing IRAC1 IRAC2 GiveUpOnN4085?
NGC4085_4088 5.61800 16.9526    
UGC07089_7094_NGC4111 6.05700 13.9070   Two stars are right next to two of the galaxies...
UGC07089_7094_NGC4111 5.79000 14.3756    
NGC4096 6.67100 14.3587   Offset ExistingTiming IRAC1 IRAC2
NGC4143 6.90800 5.86466 FLAGGED! Offset Timing IRAC1 IRAC2
NGC4151 4.14500 9.86687 FLAGGED! Offset NoTiming IRAC1 IRAC2
NGC4203 6.88900 3.84812 FLAGGED! Too Close...
UGC07577_7608 5.67100 25.0088   On the edge suggest delete TIMING2
NGC4460 6.49500 11.0601   Offset Timing IRAC1 IRAC2
NGC4460 6.11700 11.0855    
NGC4460 5.74000 19.9140    
NGC4861 5.35000 16.6892   NoOffset Timing IRAC1 IRAC2
NGC4861 5.43600 18.9338    
NGC5523 6.79900 9.60591 FLAGGED! Offset ExistingTiming IRAC1 IRAC2

NOTE:'Cliff's Criterion' is a rule of thumb Cliff Johnson made for LVL. Any star with distance < 10' and k_mag < 7 or distance < 12' and k_mag < 6 is flagged for investigation (Cliff used 6.5 and 5 k_mag respectively but we have longer exposure times so I modified it slightly).

Other Notes

The UGC07089_7094_NGC4111 field looks like it may not be centered. That is because it is hard to see the third galaxy in the lower part of the image.

UGC08839 looks too dim for its coverage, but that is only because it is dim in the DSS image used to generate the AOR field.