### Document

```U波段数据测试

2012.8

(选择无污染的恒星源)
SCUSS Psf星等-sdss psf星等比较
• 选取psf和sdss测光误差小于0.02的点源

-0.0235296
-0.0201109
-0.0206930
-0.0179725
-0.0182189
-0.0161284
-0.0159997
-0.0144610
-0.0127202
-0.0119203
-0.0107648
-0.0102608
-0.00756815
-0.00697094
-0.00372003
-0.00575806
-0.00268271
-0.000274569
0.00396153
0.0685271
0.0675444
0.0669077
0.0673477
0.0644946
0.0644588
0.0637689
0.0630867
0.0627128
0.0638426
0.0608993
0.0567401
0.0612554
0.0642833
0.0684189
0.0628232
0.0647498
0.0672220
0.0731668
Bertin星等-sdss星等随星等的变化
• 选取bertin和sdss测光误差小于0.02的点源
•
Bertin的弥散比psf要小

-0.0259105
-0.0246121
-0.0242445
-0.0221311
-0.0219102
-0.0204170
-0.0199481
-0.0185407
-0.0170448
-0.0163680
-0.0151868
-0.0138376
-0.0118984
-0.0113060
-0.0100813
-0.00901517
-0.00822791
-0.00658884
-0.00761263
0.0308886
0.0308727
0.0312536
0.0305853
0.0306141
0.0311835
0.0307561
0.0316147
0.0313975
0.0322766
0.0316561
0.0325358
0.0338848
0.0351563
0.0361410
0.0362183
0.0380520
0.0422230
0.0389670
Robust linear fit
uscuss-usdss = -0.146144 +
0.00746879*usdss

• 取bertin和sdss测光误差小于0.02的所有点源
U-gqq取 bin，星等差

-0.00588882 0.0302815
-0.00873136 0.0299288
-0.0132765 0.0291165
-0.0180792 0.0287952
-0.0215231 0.0288804
-0.0226429 0.0290305
-0.0226331 0.0299222
-0.0207492 0.0310095
-0.0192056 0.0316362
-0.0158874 0.0323331
-0.00962605 0.0354208
0.00237520 0.0401567
0.0309993 0.0590625
0.0173266 0.0440410
Robust poly fit
uscuss-usdss = 0.04435340.0806870*(usdss-g) +
0.0249528*(usdss-g)2
(适用于0.8<u-g<2.8)

uscuss = (uscuss+0.146144)/ (1+
0.00746879)
U-gqq取 bin，星等差

0.00924011 0.0291652
0.00746672 0.0294777
0.00400803 0.0284212
-0.000542520 0.0281475
-0.00377328 0.0281775
-0.00499911 0.0283190
-0.00525310 0.0292280
-0.00376548 0.0304447
-0.00255169 0.0312807
0.000466597 0.0322601
0.00630103 0.0351254
0.0179596 0.0394676
0.0453667 0.0580910
0.0311774 0.0437415
Robust poly fit
uscuss-usdss = 0.0548322 0.0715310*(usdss-g) +
0.0220192*(usdss-g)2
(适用于0.8<u-g<2.8)

• http://www.sc.eso.org/~asmette/gaia/

• 随机下载了大约4000个sdss类星体的光谱，将它们整体蓝移0.3，使得
sdss的光谱可以卷积bok u和sdss u的滤光片
Scuss与sdss之间星等差随红移的变化

```