The Arecibo Legacy Fast ALFA Survey

Arecibo Observatory

Examples of targets for the A2707 Jan 2013 observing run

During the Jan 2013 workshop, we will be conducting observations with L-band wide to confirm the reality of ALFALFA sources without optical counterparts. We will also take a look at a few signals with low signal-to-noise ratio and low heliocentric velocity which might have optical counterparts. Here are a few examples of such targets.

Below are (1) the ALFALFA "catalog" file (referring to the product of our routine GALCAT, not what we publish; these data have not been published!), (2) the summary graphical images (generated by our software) and (3) links to public database images and the NED. Use this information to understand why we want to reobserve these and similar sources and what their significance would be if, in fact, they prove to be real signals. (Before you tackle the targets below, make sure you have done the Using SDSS, NED and Cataloging HI sources in ALFALFA exercises.)

The ALFALFA "catalog" file for the six example targets:

### Formatted ALFALFA Catalog generated: Sun Nov 18 10:59:25  by martha      Example targets for UAT Jan'13
#Object              AGC     Other Ellipse Center  dRA dDEC Optical Center   hsize   v50 verr   W50 werr   SintP  Serr  Sintmap   SN   rms   code   grid
#                                  J2000                    J2000                    km/s                  Jykm/s                      mJy
HI081700.9+170356 189207           081701.4+170413   0   0  000000.0+000000    4.7   419    3    20    7    0.43  0.05    0.42    6.8  2.93   1     0820+17a
HI081801.6+004057      0           0818 1.7+004109   0   0  0000 0.0+000000    1.2 -1340    4    14    7    0.45  0.06    0.33    7.7  3.10   3     0820+01a 
HI111307.9+291615 219502           111309.5+291623 -46 -41  111313.1+291704    5.0   601    4    23    7    0.22  0.04    0.26    3.8  2.49   4     1116+29a
HI124614.3+020130 224303           124614.2+020131 -32 -75  124616.4+020246    6.9   902    3    15    7    0.28  0.07    0.31    3.3  4.55   5     1244+01a
HI125722.3+025937 229213           125722.5+025941   0 -13  125722.5+025955    0.8  2873    5    60    9    0.38  0.05    0.42    4.3  2.54   4     1300+03a
HI131623.7+161640 239077           131624.2+161643   0   0  000000.0+000000    0.6   353    5    16   10    0.28  0.03    0.25    6.4  2.24   1     1316+17a

Click here to download this file

The ALFALFA spectra: (click on image to enlarge or download):
Links to relevant images/NED for these targets:
HI081700.9+170356
0817014+170413 124.2558 17.0703 DR7Navigate DR9Navigate SkyView.03 SkyView.10 DSS2red.03 DSS2blu.03 DSS2red.10 DSS2blu.10 NED1.0
HI081801.6+004057
0818017+004109 124.5071 0.6858 DR7Navigate DR9Navigate SkyView.03 SkyView.10 DSS2red.03 DSS2blu.03 DSS2red.10 DSS2blu.10 NED1.0
HI111307.9+291615
1113095+291623 168.2896 29.2731 DR7Navigate DR9Navigate SkyView.03 SkyView.10 DSS2red.03 DSS2blu.03 DSS2red.10 DSS2blu.10 NED1.0
HI124614.3+020130
1246142+020131 191.5592 2.0253 DR7Navigate DR9Navigate SkyView.03 SkyView.10 DSS2red.03 DSS2blu.03 DSS2red.10 DSS2blu.10 NED1.0
HI125722.3+025937
1257225+025941 194.3438 2.9947 DR7Navigate DR9Navigate SkyView.03 SkyView.10 DSS2red.03 DSS2blu.03 DSS2red.10 DSS2blu.10 NED1.0
HI131623.7+161640
1316242+161643 199.1008 16.2786 DR7Navigate DR9Navigate SkyView.03 SkyView.10 DSS2red.03 DSS2blu.03 DSS2red.10 DSS2blu.10 NED1.0

Some questions (to get you thinking)

What do the columns in the ALFALFA "catalog" file contain? (Hint See our documentation, and of course, understand what we mean!)
What does each graph and the table in the graphical image summary represent?
Notice that the source names (e.g. HI081700.9+170356) appear to contain coordinates, but the coordinates do not match the coordinates used to generate the links to optical images. Why not? (Hint: How do we calibrate the positions in ALFALFA, i.e. tie them to other astrometric standards? What do the different coordinates refer to?)
What questions do you have about these sources and why we want to observe them???

Last modified: Mon Nov 19 10:06:28 EST 2012 by martha