EROSITAwiki: attachment:eRosita_DE_multiwavelength_overlap.txt of WikiSandBox

   1 ==============================================
   2 Multi-wavelength coverage over the eROSITA sky
   3 Tom Dwelly (dwelly@mpe.mpg.de), 07/05/2013
   4 ==============================================
   5 
   6 This document presents the calculation of how much of the German 
   7 eROSITA sky is jointly covered by various existing and future large-area 
   8 multi-wavelength surveys.
   9 
  10 
  11 Method 
  12 ====== 
  13 First I collect/construct footprints of various wide area sky surveys
  14 in the form of 'mangle' polygon mask files. mangle is the masking software
  15 used within the SDSS collaboration to define the footprint 
  16 of the SDSS imaging and spectroscopic observations.
  17 See http://space.mit.edu/~molly/mangle/ for details of mangle.
  18 
  19 A Monte-Carlo approach is then used to calculate the areal overlap
  20 between various survey footprints. A wrapper script around the mangle
  21 task 'polyid' is used to determine what fraction of a large set of
  22 randomly distributed points lie within the bounds of a sequence of
  23 mangle mask(s). The script allows the joint area of any set of mangle
  24 masks to be evaluated (combined with logical AND or NAND). The sky
  25 area contained within those masks is then 4pi*Nin/Ntotal, where Nin is the
  26 number of trials within the mask, and Ntotal is the total number of
  27 trials.  Note that the fractional uncertainty on the area estimate
  28 is approx sqrt(Nin*(1-Nin/Ntotal))/Ntotal. So for a total of 1e6
  29 trials, and a region of interest subtending 20000 deg^2, we have an
  30 uncertainty of ~20deg^2.
  31 
  32 
  33 Large area surveys and details of their sky coverage
  34 ====================================================
  35 
  36 eROSITA
  37 -------
  38 I assume that German eROSITA sky covers 180deg < l < 360deg with no 
  39 'demilitarized zone' between the DE and RU sky areas. 
  40 Extra-galactic sky is assumed to lie at |b| > 20deg.
  41 
  42 SDSS - (e)BOSS 
  43 --------------
  44  
  45 For this we use the SDSS-DR8 BOSS targeting footprint, which is
  46 essentially the extra-galactic part of the full SDSS imaging footprint
  47 (which includes connecting strips crossing the Galactic plane). It is
  48 my understanding that this can also be considered to be a superset of the
  49 eBOSS tiling area. The BOSS/eBOSS targeting footprint is supplied as
  50 a mangle polygon file:
  51 http://data.sdss3.org/sas/dr9/boss/lss/boss_survey.fits 
  52 See description here: http://www.sdss3.org/dr9/algorithms/boss_tiling.php
  53 I have not accounted for areas affected by bad imaging, bright stars etc.  
  54 The sky area covered by the above (e)BOSS targeting mask is 10778deg^2.
  55 
  56 
  57 UKIDSS 
  58 ------ 
  59 I use the UKIDSS-DR10 LAS K-band footprint to describe the
  60 area usefully covered by the UKIDSS survey. These mask are available from the WSA: 
  61 http://surveys.roe.ac.uk/wsa/coverage-maps.html and specifically:
  62 http://surveys.roe.ac.uk/wsa/coverage-maps/UKIDSS/DR10/las-K-DR10.fits 
  63 Unfortunately the UKIDSS coverage maps are supplied in HEALPIX MOC (Multi-order
  64 coverage) map format, but I've written a shell script to allow conversion
  65 from MOC to mangle polygon format.  The sky area covered by the
  66 las-K-DR10.fits coverage mask is ~3600 deg^2.
  67 
  68 A straw-man UKIRT Hemisphere Survey (UHS) would complete (in J only)
  69 the remaining sky between 0<Dec<+60deg which is not already covered by
  70 UKIDSS projects.
  71 
  72 
  73 
  74 VST - public surveys
  75 --------------------
  76 I have constructed mangle masks from the following survey descriptions:
  77 
  78 http://www.eso.org/sci/observing/PublicSurveys/sciencePublicSurveys.html
  79 VST-KIDS – description here: http://www.astro-wise.org/projects/KIDS/
  80 RA bounds            Dec bounds
  81 ----------------------------------
  82 10h00 < RA < 15h00  -5 < Dec <  +3
  83 15h00 < RA < 15h52  -3 < Dec <  +3
  84 08h40 < RA < 09h08  -3 < Dec <  +1
  85 22h00 < RA < 03h30 -35 < Dec < -25
  86 
  87 VST-ATLAS - description here: http://astro.dur.ac.uk/Cosmology/vstatlas/
  88 RA bounds            Dec bounds
  89 ----------------------------------
  90 21h30 < RA < 04h00 -40 < Dec < -10
  91 10h00 < RA < 15h30 -20 < Dec <  -2
  92 10h00 < RA < 15h00 -29 < Dec < -20
  93 
  94 
  95 VISTA - public surveys
  96 ----------------------
  97 I assume that the VISTA wide area extra-galactic surveys 
  98 (VHS, VIKING etc) will between them cover the entire 
  99 sky South of Dec=0deg and with |b|>5.5deg.
 100 
 101 VISTA-VIKING - is assumed to cover the same sky area as VST-KIDS, see above. 
 102 
 103 
 104 Dark Energy Survey (DES)
 105 ------------------------
 106 I have built a mangle mask from the following DES survey description
 107 www.darkenergysurvey.org/survey/des-description.pdf‎
 108 
 109 Table 1: Wide-Area Survey Boundaries:
 110 Sub-Area          RA bounds(deg)     Dec Bounds(deg)
 111 ----------------------------------------------------
 112 SPT              -60 < RA < 105    -65 < Dec < -40
 113 Viking           -30 < RA <  60    -40 < Dec < -25
 114 Round 82          -3 < RA <  45    -25 < Dec <  +3
 115 Stripe 82        -43 < RA <  -3     -1 < Dec <  +1
 116 
 117 PanSTARRS-1/2
 118 -------------
 119 I have assumed that the PanSTARRS 3pi survey will cover the whole 
 120 sky North of Dec=-30deg.
 121 
 122 SkyMapper
 123 ---------
 124 I have assumed that the SkyMapper Southern Sky Survey will cover the 
 125 whole sky South of Dec=0deg.
 126 
 127 4MOST spectroscopic survey
 128 --------------------------
 129 I have assumed that a 4MOST extra-galactic dark/grey time survey will 
 130 cover the whole |b|>25deg sky between the limits -70<Dec<+20deg 
 131 (Total ~16000 deg^2)
 132 
 133 WEAVE Survey
 134 ------------
 135 I make an optimistic guess for the coverage of a WEAVE-LOFAR survey: 
 136 that is will cover all extra-galactic (|b|>25deg) sky North of Dec=+10deg 
 137 (Total ~9440 deg^2)
 138 
 139 Further into the future
 140 -----------------------
 141 LSST  ->  http://www.lsst.org/lsst/science/science-faq#q2
 142 - All sky south of Dec=+10deg
 143 
 144 Euclid - (Rough guess) - all extra-galactic sky with |b|>35deg => 17000deg^2
 145 
 146 Results
 147 =======
 148 
 149 Here is a summary of the aforementioned survey regions and their areas. 
 150 All numbers should be accurate to +-20deg^2 or better
 151 
 152 |--------------------------------------------------------------------|
 153 |Survey              | Total    |       In eROSITA-DE sky            |
 154 |                    |          |------------------------------------|
 155 |                    |          |  any b   |  |b|>20deg  | |b|<20deg |
 156 |                    | (deg^2)  | (deg^2)  |    (deg^2)  |  (deg^2)  | 
 157 |--------------------------------------------------------------------|
 158 |eROSITA             |  41000      20600         13550        7050   |
 159 |(e)BOSS footprint   |  10780       3630          3550          80   |
 160 |UKIDSS-LAS-K-DR10   |   3600       1900          1890          10   |
 161 |UKIDSS-UHS-J        |  17870       4780          3490        1290   |
 162 |VST-ATLAS           |   4690       3280          3280           0   |
 163 |VST-KIDS            |   1500       1120          1120           0   |
 164 |VISTA-VHS & VIKING  |  18620      14220         10090        4230   |
 165 |VISTA-VIKING        |   1500       1120          1120           0   |
 166 |DES                 |   5000       3470          3440          30   |
 167 |PanSTARRS           |  30920      10930          8100        2830   |
 168 |SkyMapper           |  20620      15850         10090        5760   |
 169 |4MOST-exgal         |  16000      10020         10020           0   |
 170 |WEAVE-LOFAR         |   9450       2080          2080           0   |
 171 |LSST                |  24210      17510         11290        6220   |
 172 |Euclid              |  17590       8780          8780           0   |
 173 |---------------------------------------------------------------------
 174 
 175 
 176 Note that it would be very easy to use my script to evaluate compound queries 
 177 such as: Calculate the sky area satisfying: 
 178 (inside eROSITA-DE) AND (inside |b|>20deg) AND (inside eBOSS) 
 179 AND (inside UKIDSS-LAS) AND (outside DES) 
 180 
 181 
 182 Visibility of German eROSITA sky from leading observatory sites:
 183 ================================================================
 184 
 185 For this exercise I have calculated the amount of eROSITA-DE sky 
 186 which is visible (within reasonable airmass limits) from various famous
 187 observatory sites. I've used the same approach as before, and have  
 188 constructed mangle masks for the potential sky visible from 
 189 nominal observatory latitudes.
 190 
 191 I approximate AM = sec(Z), where Z is the zenith distance.
 192 Therefore, if AM<1.5 then Z<48.2deg, if AM<2 then Z<60.0deg.
 193 
 194 -----------------------------------------------
 195 Optical/IR
 196 -----------------------------------------------
 197 Site Name          Latitude     Telescopes
 198 SAAO, Sutherland   -32d 23'     SALT      
 199 AAO,Siding Spring  -31d 17'     AAT
 200 Cerro Pachon       -30d 15'     Gemini-S,SOAR
 201 Cerro Tololo       -30d 10'     Blanco(DES)
 202 La Silla           -29d 15'     NTT,3.6m,MPG2.2m ...
 203 Las Campanas       -29d 01'     Magellans
 204 Paranal            -24d 38'     VLT,VST,VISTA 
 205 Mauna Kea          +19d 50'     Keck,Subaru,Gemini-N,UKIRT,CFHT...
 206 La Palma           +28d 46'     GTC,WHT,TNG,INT...
 207 Kitt Peak          +31d 57'     WIYN
 208 Apache Point       +32d 47'     SDSS,ARC3.5m
 209 Xinglong           +40d 24'     LAMOST
 210 -----------------------------------------------
 211 
 212 -----------------------------------------------
 213 Radio/mm
 214 -----------------------------------------------
 215 Site Name          Latitude     Telescopes
 216 Northern Cape      -30d 50'     MeerKat
 217 Murchison          -26d 42'     ASKAP
 218 Chajnantor         -23d 01'     ALMA, APEX, ACT
 219 Socorro            +34d 05'     VLA
 220 LOFAR              +52d 54'     LOFAR         
 221 Westerbork         +52d 55'	WSRT-APERTIF	   
 222 -----------------------------------------------
 223 
 224 Results
 225 =======
 226 Here are the sky areas covered for a representative set of 
 227 telescope latitudes. All sky areas should be accurate to 
 228 +-20deg^2 or better
 229 
 230 |-------------|-----------------------------------------|
 231 |             |         Area in eROSITA-DE sky          |
 232 |  Telescope  |-----------------------------------------|
 233 |  latitude   |         any b      |     |b|>20deg      |
 234 |             |--------------------|--------------------|
 235 |             |   AM<1.5 | AM<2.0  |   AM<1.5 | AM<2.0  |
 236 |   (deg)     |  (deg^2) | (deg^2) |  (deg^2) | (deg^2) |
 237 |-------------|-----------------------------------------|
 238 |  -30deg     |   18290     19970      11760     13000  |
 239 |  -25deg     |   18420     20280      11850     13240  |
 240 |  +20deg     |   10540     13300       7830      9510  |
 241 |  +30deg     |    8360     10960       6260      8120  |
 242 |  +50deg     |    4450      6670       3240      4930  |
 243 |-------------|-----------------------------------------|
 244 
 245 
 246 
 247 end
 248 ---