We present sky-SB measurements on all images in the SKYSURF database. For an overview on the project, refer to Windhorst et al. (2022). For a description of sky-SB measurement algorithms and a summary of sky-SB results, refer to O'Brien et al. (2022).
There is 1 csv file corresponding to each Hubble Space Telscope (HST) filter. Each csv file contains 1 sky-SB measurement per detector (i.e. 1 sky measurement for each WFC3/IR image and 2 sky measurements for each WFC3/UVIS and ACS/WFC image).
| Column Name | Description |
|---|---|
| File | File name that sky-SB was measured on |
| Root | Root name of file that sky-SB was measured on |
| Extension | FITS file extension that sky-SB was measured on |
| Sky_e or Sky_e/s | Measured sky-SB, in units of electrons or electrons/sec |
| RMS_e or RMS_e/s | Measured sky-SB RMS, in units of electrons or electrons/sec |
| Error_e or Error_e/s | Uncertainty in sky-SB, in units of electrons or electrons/sec |
| Flag | Flag associated with measurement (see Table 2 below) |
| N_bad_regions | Number of bad sub-regions in sky-SB measurement (not including bad pixel sub-regions) |
| N_bad_pixel_regions | Number of bad pixel sub-regions in sky-SB measurement |
| N_good_regions | Number of good sub-regions in sky-SB measurement |
| N_total_regions | Total number of sub-regions in sky-SB measurement |
| Mean_x_px or Mean_y_px | Mean x or y pixel position of good sub-regions used in sky-SB measurement |
| Std_x_px or Std_y_px | Std of x or y pixels of good sub-regions used in sky-SB measurement |
| Q1_Sky_e/s or Q1_RMS_e/s | Sky-SB or sky-SB RMS in WFC3/IR Quadrant 1 (top left) |
| Q2_Sky_e/s or Q2_RMS_e/s | Sky-SB or sky-SB RMS in WFC3/IR Quadrant 2 (bottom left) |
| Q3_Sky_e/s or Q3_RMS_e/s | Sky-SB or sky-SB RMS in WFC3/IR Quadrant 3 (bottom right) |
| Q4_Sky_e/s or Q4_RMS_e/s | Sky-SB or sky-SB RMS in WFC3/IR Quadrant 4 (top right) |
| Quad_Left_Sky_e or Quad_Left_RMS_e | Sky-SB or sky-SB RMS in left half of ACS/WFC or WFC3/UVIS chip |
| Quad_Right_Sky_e or Quad_Right_RMS_e | Sky-SB or sky-SB RMS in right half of ACS/WFC or WFC3/UVIS chip |
| Expected_RMS_e or Expected_RMS_e/s | Expected RMS based on Poisson and Gaussian noise |
| RA_J2000 | RA of image |
| DEC_J2000 | DEC of image |
| Target_Name | Target name associated with image |
| Start_JD | Start Modified Julian Date associated with image |
| Start_Time | Start time associated with image |
| Average_Earth_Limb_Angle | Average Earth Limb Angle during the exposure |
| Ecliptic_Latitude | Ecliptic Latitude of exposure |
| Ecliptic_Longitude | Ecliptic Longitude of exposure |
| Galactic_Latitude | Galactic Latitude of exposure |
| Galactic_Longitude | Galactic Longitude of exposure |
| Exp_Time | Exposure Time |
| Moon_Angle | Moon Angle |
| Sun_Altitude | Sun Altitude |
| Sun_Angle | Sun Angle |
| CAL_VER | calwf3 version used to reduce file |
| Sensitivity_Jy/(e/s) | Inverse sensitivity in units of Jy/(e/s) |
| Sensitivity_SCI1_Jy/(e/s) | Inverse sensitivity of the first science extension (Chip 2) in units of Jy/(e/s) |
| Sensitivity_SCI2_Jy/(e/s) | Inverse sensitivity of the second science extension (Chip 1) in units of Jy/(e/s) |
| Sensitivity_Err_Jy/(e/s) | Error in zeropoint from Calamida et al. (2022) |
| Sky_MJy/sr | Measured sky-SB, in units of MJy/sr |
| Sky_rms_MJy/sr | Measured sky-SB rms, in units of MJy/sr |
| Error_MJy/sr | Uncertainty in sky-SB, in units of MJy/sr |
| Sky_MJy/sr_thermcorr | Measured sky-SB, in units of MJy/sr, with Thermal Dark signal subtracted |
| Sky_MJy/sr_no_thermcorr | Measured sky-SB, in units of MJy/sr, with Thermal Dark signal NOT subtracted |
| Therm_Corr_MJy/sr | Thermal Dark signal in units of MJy/sr |
| Therm_Corr_e/s | Thermal Dark signal in units of e/s |
| Flag | Flag Description |
|---|---|
| 0 | No flag |
| 1 | More than 30% of sub-regions are flagged as bad |
| 2 | The sky-SB rms is higher than 2.5 times the expected rms |
| 4 | Image flagged via manual inspections |
| 8 | Exposure within 20 degrees of the galactic plane |
| 16 | Exposure with an Earth Limb Angle less than 40 deg |
| 32 | Exposure with a Sun Altitude greater than 0 deg |
| 64 | Extended object identified from Target Name ('M31', 'SMC', 'LMC', 'M32', 'M33', 'NGC', 'N44') |
| 128 | Persistence affects more than 1% of pixels in the image |
| 256 | Sun Angle less than 80 degrees |