Your SQL command was:
SELECT TOP 10 fld.run, fld.avg_sky_muJy, fld.runarea AS area, ISNULL(fp.nfirstmatch,0) 
FROM ( 
 SELECT run, sum(primaryArea) AS runarea,
 3631e6*avg(power(cast(10. as float),-0.4*sky_r)) as avg_sky_muJy
 FROM Field
 GROUP BY run 
) AS fld 
LEFT OUTER JOIN ( 
 SELECT p.run, count(*) AS nfirstmatch
 FROM FIRST AS fm
 INNER JOIN photoprimary as p
 ON p.objid=fm.objid
 GROUP BY p.run 
) AS fp 
ON fld.run=fp.run 
ORDER BY fld.run 

Your query output (max 500,000 rows):

runavg_sky_muJyareaColumn1
9428904048.33421940.0449705088487448298
109138591386.0074769.511612568607372127
12544153130.3569720.001503232682230150
21121416142.47654775.92509366060802129
24017537965.498629900
24111769171.148195300
25010101392.32654590.881671633523299839
25113858667.3099260.05832451141645190
25621605847.63757080.0005068677264357060
25932534235.683248422.0192458866879511