Updating GALFA and Planck
By Elijah Bernstein-Cooper, June 28, 2015, 0 comments.

## Data Update

### GALFA

We are now using the GALFA data release 2. Some words from Josh Peek about the data:

• Credit to Kevin Douglas, Brian Babler, Yong Zheng and Josh Peek

• The data are largely taken from commensal observations with GALFACTS, and are in our shallowest (“gear 6”) mode, which results in noise of about 140 mK / 1 km/s channel, covering almost all of the Arecibo sky. The data are supplemented from three sources to fully fill in the Arecibo sky:

1. A small region of sky near RA = 60, dec 10 is filled in with data from DR1.

2. A small region near RA 50, dec 18 is filled in with data provided by the EBHIS collaboration. These data are marked in the equivalent T.fits files with a -1

3. Small holes throughout are patched with data from LAB. These data are marked in the equivalent T.fits files with a -2

The GALFA DR1 and DR2 have comparable noise present both ranging from $T_b \sim 0.1$ K to $0.3$ K.

### Planck

We will now be using the $\tau_{353}$ map only instead of the Radiance + $\tau_{353}$ combined map. This is because the radiance map is only accurate for the most diffuse regions where the interstellar radiation field does not vary much. The dust opacity (which $\tau_{353}$ depends on) is shown to vary less than the radiation field for molecular clouds. See Section 6.3 and Figure 24 of the Planck paper which shows $\tau_{353}$ correlates better with 2MASS stellar extinction maps in Taurus than the radiance.

## Perseus Intercept Test

Below are likelihood spaces for Perseus.

### Planck Results

Judging by the $A_V$ background of all three clouds, Perseus seems to have the most constant background $A_V$. It is odd that there is no intercept calculated however, because inspecting the map visually, it looks like there is at least a $0.6$ mag background in the Planck map.

### Lee+12 Results

We expect that the intercept be $0$ mag since the background has already been subtracted from Perseus manually. Indeed we have agreement, no intercept was found.

## 2MASS / Planck Relationship

Here is a 2D histogram plot including all three clouds of Planck $A_V$ vs. 2MASS $A_V$. The Planck map is systematically offset from the 2MASS values. An empirical fit for each of the three clouds will come tomorrow.