15th Dec, 2005UKIDSS SciVer meeting, Edinburgh1 UKIDSS LAS Image Classification Analysis and Some Miscellaneous Issues Richard McMahon Bram Venemans Institute of Astronomy

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh2 Data used SDSS Classifications –Photometric classifications (DR4) –Spectroscopic classifications (DR4 and DR3QSO) UKIDSS –LasDetection Class ClassStat –LasSource Class, ClassStat for each band MergedClass

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh3 Y seeing distribution See zero seeing data What is pixel scale?

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh4 K seeing distribution

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh5 Issues Seeing units in WSA are in ‘pixels’. –Interleaved scale is 0.2 arcsec pixel; JHK –Y scale is 0.4 –Would be nicer is WSA had the seeing also in arcsecs? Maybe it does? Some seeing values are 0.0 pixels –What does this mean? –Is it documented

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh6 SDSS DR4 Spectral Classifications versus UKIDSS class 2101 objects with SDSS DR4 spectra (Table=SpecPhoto ) SDSS imaging classifications –1806 classified in SDSS Photo as galaxies (type=6) –295 classified in SDSS Photo as stellar (type=3) SDSS Spectral classifications (SpecClass)Number 0 - Spectrum of blank sky/unknown (2) 1 – Spectrum of a star(94) 2 – Spectrum of a galaxy (1679) 3 – Spectrum of a QSO (z<2.3)(122) 4 – Spectrum of a high redshift(z>2.3) QSO(13) 5 – Spectrum of blank sky 6 – Late type star (M or later)(34) 7 – Emission line galaxy

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh7 SDSS Photo and Spectro classifications (2101 objects) 6/1679 = 0.4% of ‘imaging’ galaxies are classified as stellar spectra. (3+2)/(91+32) = 4% of stars are classified on SDSS images as galaxies 26/(96+13) = 23% of qsos classified as galaxies –Mainly due to host galaxies in low redshift qsos Red=galaxy Blue=stellar

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh8 UKIDSS LAS Y band class (1151 objects) 10/854=1% of galaxies are miss-classified (2+4)/(55+19)=8% of stars are miss-classified 21/59=36% of z<2.3 QSOs are classified as galaxies – QSOs hosts visible to higher redshifts in IR than in optical data; upto z=1 2/7 of z>2.3 QSOs are classified as galaxies –Need to look at SDSS spectra since could be miss- classified spectra Black=noise Orange=Probable star Red=galaxy Blue=stellar

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh9 UKIDSS K band class (2015 objects) (7/1615+7)=0.4% of galaxies are miss-classified (6+10)/(75+34)=15% of stars are classified as galaxies (42/ ))=36% of z<2.3 QSOs are classified as galaxies – QSOs hosts visible to higher redshifts in IR than in optical data 2/12 of z>2.3 QSOs are classified as galaxies –Need to look at SDSS spectra since could be miss- classified spectra Black=noise Orange=Probable star Red=galaxy Blue=stellar

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh10 z>2.5 QSOs with Y non-stellar classifications z=3.28 Y class=1 Stellar(-1) in J,H,K z=2.64; Yclass=0(noise) ☺ J_1Class=1 Stellar(-1) in H, K z=2.95 Y class=1 Stellar(-1) in J,H,K Seeing: 2.1pix Seeing=2.4pix Seeing=1.7pix Need to look further into these

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh11 Some Issues SDSS ‘sample’ is not representative in the sense that it is biased towards galaxies and QSOs. SDSS spectral class are pipeline based and I have not used the ‘spectral’ class quality information However, there are SDSS ‘control’ fields where a random sample of ‘all’ objects have been observed.

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh12 Conclusions Seeing in arcsecs as well as pixels please Classifications OK on average –Probable as good as SDSS bearing in mind that SDSS sample have s/n(SDSS)>10 and multiband, whereas no s/n threshold in UKIDSS data –Seem to be more galaxies classified as stars than in SDSS 4% in SDSS, 8% in Y, 15% in K (statistical/cosmic effect) SDSS have some classification ‘calibration’ fields that are within the 2005A/B data(I think) Other requests –Can the SQL query be echoed on the results page –Can it also be added to the output file –More than 100 columns for html output –Larger output disk quota but could be deleted after 12hrs –PetroRad in the LasSource table (also HallRad, KronRad etc)

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh13 Other Issues Ra, Decs in degrees rather than as radians in the FITs files 64bit integers as 64bit integers and not as characters Transparency via nominal Zpt histogram by band

15th Dec, 2005UKIDSS SciVer meeting, Edinburgh14 TODO Notes Plot redshift and n(m) for stars and galaxies for the image classification analysis