|Here is a small subset of the ALFALFA catalog containing the currently available spring data south of Dec < +04 degrees. Additionally, here are some screen shots of LOVEDATA screens of two objects contained in the subcatalog. Refer to this subcatalog and these figures in answering the following questions. a.   The HI profile is often two-horned. Sometimes it has a Gaussian shape. Under what circumstances would be expect to see a Gaussian shape, rather than the characteristic two horns? b.   How is the profile width, W50, measured on a two-horned profile? c.   What is meant by "rms"? d.   What is meant by "SN"? e.   In the GRIDVIEW displays, what causes the patterns of dark blue dots in the right hand panel? f.   What is the HI source name of AGC214473? g.   Why isn't the "position" in the HI source name the same as the "ellipse center" position? h.   What grid contains AGC 214473? i.   What is the HI mass of AGC 214473? j.   What is the heliocentric velocity of HI123117.1+035049? k.   What is unusual about AGC 227983? l.   There are 3 HI emission features in the GALCAT display of the spectrum of AGC 227983. What do they arise from?||
|HI centroid (J2000)||HI flux||cz||W50||SN||OC coordinates||Your comments|
|014106.4+271903||0.69||    274||  26||13.1|| || |
|095452.2+142907||0.61||12557||117||  7.3|| || |
|123120.9+050402||0.65||  9873||151||  4.9|| || |
|152240.3+055017||0.44||  1796||  24||  9.0|| || |
|160745.2+272220||0.89||  7602||  84||10.9|| || |
SELECT p.ra, p.dec,s.z,s.zerr,p.petroR90_r,p.expAB_r, p.petroMag_u,p.petroMag_r, p.objID FROM PhotoObj p, SpecObj s, SpecLine l WHERE p.SpecObjID = s.SpecObjID AND p.SpecObjID = l.specobjID AND s.specClass=2 AND l.lineID = dbo.fSpecLineNames('Ha_6565') AND p.objID=588010358007595145
Here are two diagrams of the current AGC
redshift distribution in the sky area
that will be contained in the future ALFALFA spring sky +03o grids.
The slices shown are bounded by 07h30m < R.A. < 16h30m
and +01.75o < Dec. < +04.25o.
The velocities here are heliocentric. Blue points illustrate the locations of galaxies of
known redshift; filled red circles mark ones with (current) HI data. ALFALFA will add
to both these diagrams. Refer to the diagrams in answering the following questions.
Note: since the ALFALFA results are not yet available, there aren't very many red points in these
diagrams! Next year, they will look much richer, especially the lower one.
a.   Identify the clusters in the distribution and find their matches in the NED b.   Identify a filamentary structure. How long (in Mpc) is it (assuming it is real)? c.   Estimate the size (in Mpc) of the apparent void centered at R.A. ~9h20m, cz ~ 14000 km/s.
Cone diagram of the full ALFALFA velocity range
Cone diagram of the inner 9000 kms/s