The All-Sky Portable (ASP) optical catalog  (2017, PASA 34, 25) 

The ASP (All-Sky Portable) catalog presents 1,163,237,190 optical objects in 100 files of 9GB total download size.  Fields are RA and Dec J2000 to tenth-of-arcsecond precision, red-blue photometry which yield magnitudes to a hundredth-of-magnitude precision, PSFs and variability indicator, and flags for proper motion, survey epoch, photometry source survey & catalog, and astrometry source survey & catalog.  Full details are in the paper and ReadMe.  ASP was published as 2017, PASA 34, 25. 

Here is the pre-print paper for the catalog.   

Here is the ReadMe , essential for its field descriptions and sample computer code (in BASIC and Python) to process the fields.   

The catalog can be downloaded from the PASA datastore at .  Web address is: If the PASA datastore is down, files can be downloaded below, at the bottom of this page.

ADS page for ASP is .   ArXiv page is .  DOI (publisher's page) is .

Use ASP to get the "O" band for Pan-STARRS ! 

Those who use Pan-STARRS data might bemoan the lack of a "u" band.  There is a quick fix, of sorts -- the POSS-I O band which is centered on 4050A.  While not exactly u, it is blueward of Pan-STARRS grizy, and overlaps the g band only about 33%.  The POSS-I survey was done in the 1950's and it covers all sky down to declination -33, which means it contains the entire Pan-STARRS sky which is down to declination -30.  ASP carries the complete digitized POSS-I survey, and individual objects can be matched from ASP to Pan-STARRS using a matching radius of 1 arcsecond.  For each object, even variable ones, POSS-I O can be calibrated to Pan-STARRS via the POSS-I E band (which is just Cousins R), as follows.  

Lupton 2005 gives the following transform for Pan-STARRS r & i  to Cousins R:   R = r - 0.2936( r - i ) - 0.1439   -- it was actually for SDSS r & i, but the SDSS & Pan-STARRS r & i are just the same, so works fine for this too.  So use the Lupton equation to get Pan-STARRS RPS , use with POSS-I E to calculate the (RPS - E) offset, add that offset to POSS-I O, and boom, you've got Pan-STARRS "o" to add to their "grizy" bands -- the individual-level calibration cancels out any variability across the epochs.  This is for the brighter objects, as POSS-I is about 2 magnitudes less deep than Pan-STARRS; it has 375M sources.

For this to work, the POSS-I O and POSS-I E bands must also be correctly calibrated to each other, and ASP does provide that.  A predecessor catalog, the USNO-B, had inconsistent offsets there.  The history is that USNO first released the USNO-A1.0 which digitized the entire POSS-I survey and was photometrically well-calibrated.  But shortly thereafter they released USNO-A2.0 for the purpose of better astrometry, but scattered photometric O-E offsets got introduced in the process, which were sadly passed onwards to the USNO-B catalog. 

However, ASP to the rescue: the ASP catalog presents the whole POSS-I data calibrated correctly to the USNO-A1.0 standard and also to the APM (which covered POSS-I away from the Galaxy) standard.  The calibrations are shown on the web pages: for USNO-B, and for USNO-A1.0

The ASP catalog gives the full POSS-I data, 375 million sources, with POSS-I O calibrated correctly to POSS-I E.  ASP always presents POSS-I photometry as the top priority, so the whole POSS-I is ready to be accessed simply by reading the red & blue magnitudes for every ASP record flagged as having POSS-I photometry. 
So that data can be mined for "Pan-STARRS o", using the above technique.  

     Get the ASP data  (and be sure to get the ReadMe)    

Here is the ReadMe , essential for its field descriptions and sample computer code (in BASIC and Python) to process the fields.   

The PASA datastore at  has infinite bandwidth to download the ASP files, but you can also get them here.

Files to download (zipped files, 5+ ASP files in each):


Eric W. Flesch, this page last edited 6 April 2021