The Arecibo Legacy Fast ALFA Survey
Principles of ALFALFA Scheduling
The objective of ALFALFA scheduling during each observing season
is to map completely, in 2 pass mode, two separate blocks of contiguous
ALFALFA tiles.
Each ALFALFA tile covers 4 degrees in Dec. and 20 min (5 degrees at the
equator) in R.A. The Right Ascension coverage corresponds to two observing
"seasons":
- The "Spring"
season focuses on observations in the R.A. range from
07h30m to 16h30m.
- The "Fall"
season focuses on observations in the R.A. range from
22h to 3h.
Given the
complexities of the Arecibo telescope schedules in practice, we have mapped
out a detailed plan of target drift(s) for each given observing session
which tries to optimize the allocation to ALFALFA in two ways:
- To maximize RA coverage over a large area contiguous in Declination
and which overlaps with the SDSS datasets in the "spring" sky.
- To insure that the 2nd pass is offset from the first by 3 months or
more so that we can use the Doppler shift of the Earth's motion around
the Sun to discriminate cosmic signals from RFI and spurious ones.
All of the declination settings
(corresponding to Beam 0 of the ALFA) for the entire ALFALFA survey have been preset.
Contiguous drifts in the 1st pass are offset from each other by 14.6'.
As part of the two-pass strategy, the
2nd pass drifts
are offset from the 1st by 7.3' in order to even out the scalloping.
ALFALFA Survey Status
Graphical summaries of completed and planned observations are available and are
updated regularly. Just click on the links below to access them.
Fall 2012 observations (in progress)
Completed Fall 2011 observations
Completed Spring 2011 observations
Completed Fall 2010 observations
Completed Spring 2010 observations
Completed Fall 2009 observations
Completed Spring 2009 observations
Completed Fall 2008 observations
Completed Spring 2008 observations
No observations in Fall 2007 (:
Completed Spring 2007 observations
Completed Fall 2006 observations
Completed Spring 2006 observations
Completed Fall 2005 observations
Completed Spring 2005 observations
Last modified: Mon Sep 10 10:49:07 EDT 2012 by martha