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COS Airglow

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In the ultraviolet, the sky background contains important contributions from airglow lines, which vary from day to night and as a function of HST orbital position. Airglow lines may be an important consideration for spectroscopic observations at wavelengths near the lines. Both FUSE and HUT observed a variety of FUV airglow lines which may be present in COS data. Please click here to view this list.

Observations

We have received requests for high-S/N observations of the geocoronal Lyman-alpha line profile observed with the G130M and G140L gratings. Such observations would allow users to model and subtract the line wings from their spectra. On this page, we provide a listing of both deliberate and serendipitous airglow observations. If you discover any others, please let us know through the HST Help Desk. To retrieve these datasets please use the HST archive.

Deliberate Airglow Observations

In these programs, COS airglow exposures were taken in parallel with STIS calibration observations.

ProposalAssociationLifetime
Position
Exposure TimeOptical ElementCentral Wavelength
11860LB871006012800sG140L1105
11999LBC40208012500sG130M1309
11999LBC40404011388sG130M1309
12414LBN6E206012900sG130M1309
12414LBN6E306012800sG130M1291
12414LBN6E406012800sG140L1105
12775LBW3E106012800sG130M1291
12775LBW3E206012800sG130M1291
12775LBW3E406022800sG140L1105
13145LC4KE106022900sG130M1291
13145LC4KE206022560sG130M1291
13145LC4KE306022900sG130M1291
13145LC4KE406022900sG130M1291
13548LCETE106022900sG130M1327
13548LCETE206022272sG130M1327
13548LCETE306022900sG130M1327
13548LCETE406022900sG130M1327
13548LCETE506022900sG130M1327
13994LCQJE306032900sG130M1291
13994LCQJE406032900sG130M1291
14429LD1CE106032900sG130M1327
14429LD1CE206032900sG130M1327
14429LD1CE306032900sG130M1291
14429LD1CE406032900sG130M1291
14833LDBUE206032900sG130M1327

Serendipitous Airglow Observations

Observations will be posted as they are released to the public.

ProposalAssociationLifetime
Position
Exposure TimeOptical Element Central Wavelength
11522LB620301011150sG130M1291
11522LB620302011150sG130M1318
11616LB6B290101954sG130M1291
11616LB6B290201954sG130M1327
11616LB6B290301642sG160M1577
11616LB6B290401642sG160M1600
11616LB6B290501642sG160M1623
11727LB5B0101012070sG130M1309
11727LB5B0102012830sG160M1623
12034LBGH040101810sG130M1309
12034LBGH040201810sG130M1327
12034LBGH040301454sG160M1589
12034LBGH0404011280sG160M1600
12034LBGH0405011495sG160M1577
12169LBIYAM01011460s G130M 1291
12426LBNM0101012800sG160M1577
12426LBNM0102012850sG160M1589
12426LBNM0103012750sG160M1600
12426LBNM0104012800sG160M1611
12426LBNM0105013350sG160M1623
12275LBH40801011381sG130M1327
12275LBH40802015926sG130M1291
12275LBH45801011381s G130M 1327
12275LBH4580201 5926sG130M 1291
12870LC1VA801026944sG140L1105
13302LC800801025460sG140L1105
13456LC9502010216549sG160M1577

Community Generated Templates

Dr. Vincent Bourrier of Geneva Observatory and his team, used a recent set of COS observations of 55 Cnc to build observational templates of four airglow lines and used them successfully to decontaminate the observations, as outlined in High-energy environment of super-Earth 55 Cnc e. Bourrier et al. have graciously offered to share these templates with the greater astronomy community through STScI. They caution that the lines in the templates are not centered on their rest wavelengths and have an arbitrary flux scaling. Users wishing to make use of these templates should fit the position and amplitude of the templates according to their observations, as these properties are specific to a given observation that was obtained with the COS G130M grating at a central wavelength of 1291 Å with the Hubble Space Telescope.

The templates can be seen in the paper in the following figures:
OI line (rest wavelength 1304.8576 Å) in Fig. 4
OI line (rest wavelength 1306.0286 Å) in Fig. 4
OI line (rest wavelength 1302.1685 Å) in Fig. 5
HI line (rest wavelength 1215.6702 Å) in Fig. 6

The four tables follow the same structure. They contain three columns:
1: The wavelength, in angstroms
2: The flux of a given geocoronal emission line, in erg/cm²/Å/s
3: The associated errors, in erg/cm²/Å/s

STScI and the COS Team have not tested these templates and while we encourage the astronomy community to make use of these products, we warn users to do so at their own risk.

LineOptical Element Central WavelengthTemplate
OI 1302G130M1291airglow_OI_1302.dat
OI 1305G130M1291airglow_OI_1305.dat
OI 1306G130M1291airglow_OI_1306.dat
HI 1216G130M1291airglow_HI_1216.dat