Instructions for reading the MEDIAN files from HSC CASJOBS

Authors: Brad Whitmore and Steve Lubow, January 19, 2017

After logging into HSC CASJOBS (see HSC use case #2 if you are not familiar with CASJOBS), click on MyDB and then set the context to HSC2v2. Under Tables you will find these two files:

 	SumMagAper2CatMed = this provides the median values for magaper2 photometry

 	SumMagAutoCatMed  = this provides the median values for magauto photometry

Click on one of these two table name and then click on the Sample box.


This shows an example of the output for SumMagAper2CatMed.

MatchID	Filter	Detector  n	MagMed	               MagMedAbsDev
1	F814W	ACS/WFC	  1	24.9360008239746	0
2	F814W	ACS/WFC	  1	24.5184001922607	0
3	F814W	ACS/WFC	  1	24.8040008544922	0

For the first 3 matchID number in HSC we find that only one observation has been
taken (i.e., n = 1), using the F814W filter and the ACS/WFC detector. The median value (the only value since n = 1) is provided in the MagMed column, and the deviation is provided (0 since only one value is present).


Similar results are found if the SumMagAutoCatMed table is provide, i.e., 

MatchID	Filter	Detector	n	MagMed	MagMedAbsDev
1	F814W	ACS/WFC	1	23.8211002349854	0
2	F814W	ACS/WFC	1	22.2679996490479	0
3	F814W	ACS/WFC	1	23.9361000061035	0


Note that the magauto values are brighter since these are total magnitudes
rather than aperture magnitudes.


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Here is the description for the SumMagAper2CatMed file, as provided in the HSC CASJOBS help file for this table.

Table SumMagAper2CatMed 

Description: This table provides Source Extractor magaper2 information for each match based on sources with valid Source Extractor aper2 magnitudes. The companion table SumPropMagAper2Cat contains other summary information for the corresponding match. The aggregate magnitude information is median based and is therefore more robust than the information given in table SumMagaper2Cat.


Columns
name 		units 		datatype 	description
MatchID 	none 		bigint 		MatchID of a match
Filter 		none 		string 		name of filter used in match
Detector 	none 		string 		name of detector used in match
n 		none 		int 		number of contributing visit based exposures
MagMed 		magnitudes 	float 		median value of the contributing aper2 magnitudes
MagMedAbsDev 	magnitudes 	float 		median absolute deviation of the contributing aper2 magnitudes


Example:
Determine a sample of 10 matches in the F814W filter of WFPC2 with more than 15 contributing magnitude values


	select top 10 * 
        from SumMagAper2CatMed 
        where Filter='F814W' and 
              Detector='WFPC2' and
              n > 15

Here is the resulting output:

10 row(s)
MatchID	Filter	Detector	n	MagMed	MagMedAbsDev
377807	F814W	WFPC2	18	23.3705005645752	0.0304546356201172
377841	F814W	WFPC2	18	24.731050491333	0.0803499221801758
377954	F814W	WFPC2	18	22.9982948303223	0.0300006866455078
377988	F814W	WFPC2	18	21.88889503479	0.0138044357299805
378054	F814W	WFPC2	18	24.3615999221802	0.04095458984375
378090	F814W	WFPC2	18	24.7952003479004	0.0494451522827148


********************
Here is the description for the SumMagAutoCatMed file, as provided in the HSC CASJOBS help file for this table.


Table SumMagAutoCatMed

Description: This table provides Source Extractor magauto information for each match based on sources with valid Source Extractor auto magnitudes. The companion table SumPropMagAutoCat contains other summary information for the corresponding match. The aggregate magnitude information is median based and is therefore more robust than the information given in table SumMagAutoCat.


Columns
name 		units 		datatype 	description
MatchID 	none 		bigint 		MatchID of a match
Filter 		none 		string 		name of filter used in match
Detector 	none 		string 		name of detector used in match
n 		none 		int 		number of contributing visit based exposures
MagMed 		magnitudes 	float 		median value of the contributing auto magnitudes
MagMedAbsDev 	magnitudes 	float 		median absolute deviation of the contributing auto magnitudes


Example:
Determine a sample of 10 matches in the F814W filter of WFPC2 with more than 15 contributing magnitude values


	select top 10 * 
        from SumMagAutoCatMed 
        where Filter='F814W' and 
              Detector='WFPC2' and
              n > 15


Here is the resulting output:

0 row(s)
MatchID	Filter	Detector	n	MagMed	MagMedAbsDev
377807	F814W	WFPC2	18	22.407995223999	0.0290498733520508
377841	F814W	WFPC2	18	23.9178447723389	0.0844001770019531
377954	F814W	WFPC2	18	22.0338001251221	0.0818948745727539
377988	F814W	WFPC2	18	21.0768957138062	0.0209493637084961
378054	F814W	WFPC2	18	23.9357500076294	0.0825042724609375