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LamostAbs

Absolute flux calibration for LAMOST Low Resolution Spectral (LRS) data.

This is the Python realization of the re-calibrating procedure for the LAMOST spectra with the SDSS/PanSTARRS1 multi-band photometric data（see reference from LAMOST Quasar Survey DR6-9 (Jin et al. 2023)）

Install this development version (in editable mode):

git clone git@github.com:wang1hm/LamostAbs.git
cd LamostAbs
python -m pip install -e .

pipeline

crossmatch with SDSS

  • upload LAMOST QSO catalog

sdss.china-vo casjob

sdss casjob

  • crossmatch and get Mag_g,Mag_r,Mag_i or [OIII]5007
## 找附近的点
SELECT
  m.name AS name,m.radeg AS ra1, m.decdeg AS dec1, n.distance,
  o.ra AS ra2, o.dec AS dec2,o.petroMag_g AS Petro_g,o.petroMag_r AS Petro_r,o.petroMag_i AS Petro_i
  FROM MyDB.turnOff AS m
  OUTER APPLY dbo.fGetNearByObjAllEq( m.radeg, m.decdeg, 3.0/60.) AS n
  LEFT JOIN PhotoObj AS o ON n.objid=o.objid

## 找最近的点
SELECT
  m.radeg AS ra1, m.decdeg AS dec1, n.distance,
  o.ra AS ra2, o.dec AS dec2,o.petroMag_g AS Petro_g,o.petroMag_r AS Petro_r,o.petroMag_i AS Petro_i
  FROM MyDB.DATA AS m
  OUTER APPLY dbo.fGetNearestObjEq(m.radeg, m.decdeg, 3.0/60.) AS n
  LEFT JOIN PhotoObj AS o ON n.objid=o.objid
  • download data
SDSS_path = './Filter/SDSS/'
mag_sdss_g = pd.read_csv(SDSS_path+'g.dat')
mag_sdss_r = pd.read_csv(SDSS_path+'r.dat')
mag_sdss_i = pd.read_csv(SDSS_path+'i.dat')
mag_sdss_z = pd.read_csv(SDSS_path+'z.dat')
mag_sdss_g.iloc=lam_g*10.
lam_r=lam_r*10.
lam_i=lam_i*10.
lam_z=lam_z*10.

Pstr_path = './Filter/Panstarr/'
mag_pstr_g = pd.read_csv(Pstr_path+'g.dat')
mag_pstr_r = pd.read_csv(Pstr_path+'r.dat')
mag_pstr_i = pd.read_csv(Pstr_path+'i.dat')
mag_pstr_z = pd.read_csv(Pstr_path+'z.dat')

crossmatch with PanSTARRS1

download LAMOST spectra

LAMOST QSO candidate由两部分，一系列文章里面都有提到。

一个是lamost pipeline分类为qso的源，一个是和组里的输入星表（组里选的quasar候选体）的源。

LAMOST spectra LAMOST的光谱数据在官网上下载的。 选择某个DR，然后选择low resolution

LAMOST dr9 这里就可以直接用ra，dec进行下载了。

download SDSS spectra

dr16.sdss

dr17.sdss

do calibration in prep

LAMOST光谱流量定标

== 使用测光数据进行流量定标：1）由于LAMOST的波长覆盖范围有限，所以只用到了gri三个波段，这三个波段可以在SDSS或者Pan-starr上获得。2）用SDSS（或者Pan-starr）的透过率曲线去卷积LAMOST光谱，就得到了对应的单色光度，用这个光谱去拟合在SDSS（或者Pan-starr）上得到的实际光度，就可以实现流量定标。

== 利用窄发射线做流量定标:这种方法是假设AGN的某些窄发射线是不发生变化的，将某个光谱乘上一个值，是的其窄线的flux和另一条光谱一致，就完成了流量定标，一般用到的窄线是[OIII]5007.

  • CaliFlux.py

  • CaliFlux_with_SDSS_mag.py

  • CaliFlux_with_PanSTAR_mag.py

  • CaliFlux_with_SDSS_OIII.py