MMT/ESO Spectrophotometric Standards with Gaia Positions and Proper Motions

Benjamin Weiner, MMT Observatory

The MMT telescope These are a set of widely-used spectrophotometric standard stars, compiled from the ESO Spectrophotometric Standards webpage at https://www.eso.org/sci/observing/tools/standards/spectra.html. Well-measured spectrophotometric standard stars are needed for astronomical flux calibration, throughput measurements, and so on. However, because they need to be placed on a slit or fiber of small angular size, accurate positions are important.

Because many spectrophotometric standards are nearby, they can have high proper motions, up to and over 0.5-1 arcsec per year. Many of these stars have moved significantly from their coordinates at epoch 2000 or at the original date of publication. If you try to slew to them in absolute coordinates, or if your instrument or guide camera has a small field of view, you will not find the star. Thus, I have compiled the stars' updated, highly accurate Gaia positions and proper motions from Gaia Data Release 2. For the 3 bright stars at g<3, proper motions were taken from the SIMBAD database at CDS and their positions were advanced to 2015.5 to match Gaia DR2.

Links are provided back to the ESO compilation of spectra and finding charts. However, because some stars have high PMs, they will have moved significantly from the finding chart position (many finding charts are from the Digitized Sky Survey and can be over 30 years old).

Star positions on this page are given for epoch 2015.5, in equinox 2000. A proper motion Javascript calculator is provided below, so that you can compute the star's position at any epoch. For observing, you will often want to compute the position at the current epoch (and in equinox 2000).

What's the difference between equinox and epoch? Equinox is the reference frame of the coordinate system, eg J2000 is oriented to the position of the north polar axis in year 2000. Epoch is the time of observation, eg where the star was at year 2015.5.


Proper motion calculator

This calculator takes as input a star's RA, Dec at a previous epoch (default 2015.5), its proper motion in RA and Dec in milli-arcsec per year, and the desired new epoch, and calculates the new coordinates for that epoch. Enter coordinates in the boxes in the upper row, or select a star from the drop-down menu to fill in the RA, Dec, PM, and enter your new epoch, e.g. 2020.5. Then click Compute, and the star's new position will appear in the lower row. The calculator uses Javascript embedded in the webpage, and it will work offline if you save this page as HTML to your computer (useful if your observatory's internet goes down).

Choose star or type in boxes:
RA/Dec at first epoch, deg Previous epoch PMs, mas/yr New epoch
RA (deg) Dec (deg) Epoch PM_RA PM_Dec Epoch
New RA (deg) New Dec (deg) New Ra/Dec (hms dms)


Table of Spectrophotometric Standard Star Gaia Positions and Proper Motions, in RA order

No. Name RA Dec (epoch 2015.5) RA, deg Dec, deg pm_RA, mas/yr pm_Dec, mas/yr parallax, mas g mag B-g, color SpecType Note ESO webpage Gaia ID
1 HR9087 00h01m49.467s -03d01m39.173s 0.45611 -3.02755 18.84 -9.70 7.14 5.06 -0.02 B7III - hr9087 2448177130188111232
2 G158-100 00h33m54.630s -12d08m01.745s 8.47762 -12.13382 157.60 -191.43 2.17 14.69 0.39 dG-K - g158_100 2375647158466154112
3 HR153 00h36m58.315s +53d53m48.728s 9.24298 53.89687 15.96 -6.76 9.19 3.57 0.03 B2IV - hr153 418001477266591744
4 CD-34d241 00h41m46.899s -33d39m08.723s 10.44541 -33.65242 -17.27 -18.72 3.60 11.10 0.26 F - cd_34241 5006170763041755264
5 BPM16274 00h50m03.883s -52d08m15.040s 12.51618 -52.13751 138.59 30.69 19.61 14.25 -0.12 DA2 Model bpm16274 4922382445088509312
6 LTT1020 01h54m50.633s -27d28m39.335s 28.71097 -27.47759 310.82 -231.98 7.30 11.34 0.32 G - ltt1020 5024640977840398848
7 HR718 02h28m09.582s +08d27m36.144s 37.03992 8.46004 23.71 -4.79 16.57 4.18 0.07 B9III - hr718 22745910577134848
8 EG21 03h10m31.132s -68d36m04.982s 47.62972 -68.60138 39.45 -103.19 96.17 11.42 -0.07 DA - eg21 4646535078125821568
9 LTT1788 03h48m22.898s -39d08m39.952s 57.09541 -39.14443 214.13 -189.45 2.75 13.01 0.27 F - ltt1788 4855735169813450624
10 GD50 03h48m50.274s -00d58m34.817s 57.20947 -0.97634 84.43 -162.96 32.04 14.04 -0.25 DA2 - gd50 3251244858154433536
11 SA95-42 03h53m43.657s -00d04m35.296s 58.43190 -0.07647 -14.79 -95.87 5.81 15.60 -0.21 DA - sa95_42 3257402879184420736
12 HZ4 03h55m22.170s +09d47m18.049s 58.84237 9.78835 173.27 -5.51 28.59 14.56 -0.05 DA4 - hz4 3302846072717868416
13 LB227 04h09m29.024s +17d07m54.052s 62.37093 17.13168 111.45 -22.02 19.94 15.38 -0.08 DA4 - lb227 45980377978968064
14 HZ2 04h12m43.617s +11d51m47.567s 63.18174 11.86321 59.18 -90.67 23.06 13.91 -0.15 DA3 - hz2 3304090857318319232
15 HR1544 04h50m36.724s +08d54m00.194s 72.65302 8.90005 1.34 -27.98 17.52 4.27 0.08 A1V - hr1544 3289827339648726272
16 G191-B2B 05h05m30.640s +52d49m50.470s 76.37767 52.83069 12.59 -93.52 18.89 11.74 -0.25 DA1 - g191b2b 266077145295627520
17 HR1996 05h45m59.899s -32d18m23.504s 86.49958 -32.30653 2.99 -22.03 2.15 5.10 -0.13 O9V Model hr1996 2901155648586891648
18 GD71 05h52m27.702s +15d53m10.547s 88.11543 15.88626 76.84 -172.94 19.25 13.03 -0.26 DA1 - gd71 3348071631670500736
19 LTT2415 05h56m25.018s -27d51m34.801s 89.10424 -27.85967 236.47 -157.22 2.55 12.09 0.23 -- - ltt2415 2910503176753011840
20 HILT600 06h45m13.371s +02d08m14.680s 101.30571 2.13741 -1.17 -0.53 0.39 10.42 0.09 B1 - hilt600 3126052883671520896
21 HD49798 06h48m04.694s -44d18m58.345s 102.01956 -44.31621 -4.11 5.67 1.97 8.21 -0.13 O6 Model hd49798 5562023884304074240
22 HD60753 07h33m27.314s -50d35m03.228s 113.36381 -50.58423 -3.12 5.31 1.43 6.64 -0.02 B3IV Model hd60753 5493730399606077440
23 G193-74 07h53m27.110s +52d29m27.510s 118.36296 52.49097 -88.37 -255.42 45.82 15.55 0.12 DA0 - g193_74 984190381489031424
24 BD+75d325 08h10m49.519s +74d57m58.097s 122.70633 74.96614 7.17 10.30 6.63 9.49 -0.16 O5p - bd75d325 1135587497636732672
25 LTT3218 08h41m31.122s -32d56m12.055s 130.37968 -32.93668 -1061.33 1345.95 117.33 11.83 0.07 DA - ltt3218 5639391810273308416
26 HR3454 08h43m13.456s +03d23m55.169s 130.80607 3.39866 -19.54 -1.00 7.61 4.21 -0.05 B3V - hr3454 3079329270187691008
27 AGK+81d266 09h21m19.096s +81d43m26.836s 140.32957 81.72412 -11.26 -51.26 3.47 11.88 -0.24 sdO - agk81d266 1144974578159253632
28 GD108 10h00m47.202s -07d33m30.805s 150.19667 -7.55856 -42.37 -1.88 1.91 13.55 -0.17 sdB - gd108 3772994667772794112
29 LTT3864 10h32m13.287s -35d37m41.783s 158.05536 -35.62827 -260.74 -4.59 3.33 12.02 0.28 F - ltt3864 5444093531284061568
30 Feige34 10h39m36.756s +43d06m08.816s 159.90315 43.10245 12.54 -25.41 4.40 11.11 -0.23 DO - feige34 781164326766404736
31 HD93521 10h48m23.512s +37d34m13.116s 162.09797 37.57031 0.22 1.72 0.51 6.97 -0.11 O9Vp - hd93521 775029739076581248
32 HR4468 11h36m40.846s -09d48m07.942s 174.17019 -9.80221 -57.30 4.18 11.26 4.63 0.02 B9.5V - hr4468 3587107658569000960
33 LTT4364 11h45m49.386s -64d50m34.818s 176.45578 -64.84301 2661.59 -344.85 215.74 11.43 0.08 C2 - ltt4364 5332606522595645952
34 HR4554 11h53m49.998s +53d41m41.161s 178.45833 53.69477 96.45 3.96 29.49 2.44 0.01 A0V Model hr4554 NA
35 Feige56 12h06m47.227s +11d40m12.558s 181.69678 11.67015 -7.43 -6.53 0.16 11.01 -0.07 B5p - feige56 3918811315733520640
36 HZ21 12h13m56.140s +32d56m31.826s 183.48392 32.94217 -100.88 30.13 6.32 14.71 0.00 DO2 - hz21 4016474027321256704
37 Feige66 12h37m23.518s +25d03m59.447s 189.34799 25.06651 1.83 -27.43 7.07 10.47 -0.17 sdO - feige66 3959631234670040704
38 LTT4816 12h38m48.889s -49d48m01.368s 189.70371 -49.80038 -557.23 -74.09 67.52 13.81 -0.00 DA - ltt4816 6127333286605955072
39 Feige67 12h41m51.782s +17d31m19.171s 190.46576 17.52199 -7.33 -37.28 3.26 11.77 -0.25 sdO - feige67 3935488605023787392
40 GD153 12h57m02.280s +22d01m49.490s 194.25950 22.03041 -38.41 -202.95 14.58 13.32 -0.24 DA1 - gd153 3944400490365194368
41 G60-54 13h00m08.609s +03d28m27.642s 195.03587 3.47435 -439.16 -865.95 60.80 15.65 0.35 DC - g60_54 3704392873140270336
42 HR4963 13h09m56.952s -05d32m20.926s 197.48730 -5.53915 -30.82 -29.69 12.02 4.27 0.13 A1IV - hr4963 3629615946329315456
43 HZ43 13h16m21.666s +29d05m53.750s 199.09028 29.09826 -157.77 -107.31 16.76 12.88 -0.36 DA1 - hz43 1461833904932026368
44 HZ44 13h23m35.178s +36d07m59.477s 200.89658 36.13319 -66.27 -4.52 2.48 11.64 -0.24 sdO - hz44 1473687671071803520
45 GRW+70d5824 13h38m49.246s +70d17m07.260s 204.70519 70.28535 -402.09 -24.61 37.71 12.79 -0.12 DA3 - grw70d5824 1686708050268594944
46 HR5191 13h47m32.248s +49d18m47.768s 206.88437 49.31327 -121.17 -14.91 31.38 1.86 -0.19 B3V Model hr5191 NA
47 CD-32d9927 14h11m46.319s -33d03m14.270s 212.94299 -33.05396 -4.14 7.12 2.61 10.39 0.17 A0 - cd_32d9927 6123935314632189568
48 HR5501 14h45m30.164s +00d43m02.053s 221.37568 0.71724 -40.42 -8.10 5.66 5.65 0.01 B9.5V - hr5501 3652142603120146560
49 LTT6248 15h38m59.373s -28d35m39.718s 234.74739 -28.59437 -233.38 -177.35 4.58 11.64 0.29 A - ltt6248 6210089815971933056
50 BD+33d2642 15h51m59.868s +32d56m54.341s 237.99945 32.94843 -14.56 0.92 0.17 10.79 -0.11 B2IV - bd33d2642 1369896865785991424
51 EG274 16h23m33.941s -39d13m46.153s 245.89142 -39.22949 77.13 0.33 77.43 11.00 -0.14 DA - eg274 6018034958869558912
52 G138-31 16h27m53.388s +09d12m08.730s 246.97245 9.20242 -96.72 -470.57 39.88 16.04 0.19 DC - g138_31 4452521234885949184
53 LTT7379 18h36m25.705s -44d18m39.384s 279.10710 -44.31094 -168.74 -159.04 9.43 10.06 0.34 G0 - ltt7379 6709878766312642944
54 HR7001 18h36m56.596s +38d47m05.536s 279.23582 38.78487 200.94 286.23 130.23 0.00 0.00 A0V - hr7001 NA
55 HR7596 19h54m44.836s +00d16m24.838s 298.68682 0.27357 39.13 -13.93 6.26 5.57 0.09 A0III - hr7596 4237169341286788096
56 LTT7987 20h10m56.441s -30d13m10.492s 302.73517 -30.21958 -340.72 -249.28 61.81 12.27 -0.08 DA - ltt7987 6749419923164242816
57 G24-9 20h13m55.414s +06d42m35.802s 303.48089 6.70995 -254.96 -582.28 43.62 15.68 0.19 DC - g24_9 4249667902270614272
58 HR7950 20h47m40.585s -09d29m45.337s 311.91911 -9.49593 31.95 -34.73 15.13 3.69 0.12 A1V - hr7950 6903096911031159424
59 LDS749B 21h32m16.660s +00d15m14.821s 323.06942 0.25412 413.23 27.27 23.40 14.66 -0.09 DB4 - lds749b 2687733913283870336
60 BD+28d4211 21h51m10.981s +28d51m49.486s 327.79575 28.86375 -34.73 -56.85 8.80 10.46 -0.19 Op - bd28d4211 1897151272994229120
61 G93-48 21h52m25.395s +02d23m14.917s 328.10581 2.38748 15.43 -300.55 44.43 12.79 -0.10 DA3 - g93_48 2693940725141960192
62 BD+25d4655 21h59m41.932s +26d25m56.752s 329.92472 26.43243 -37.46 -41.67 8.48 9.65 -0.15 O - bd25d4655 1796648870766546944
63 NGC7293 22h29m38.588s -20d50m13.798s 337.41078 -20.83717 38.87 -3.42 4.98 13.48 -0.25 V.Hot - ngc7293 6628874205642084224
64 HR8634 22h41m27.802s +10d49m52.727s 340.36584 10.83131 78.28 -10.64 14.28 3.30 1.22 B8V - hr8634 2717594072113581696
65 LTT9239 22h52m41.122s -20d35m37.867s 343.17134 -20.59385 78.87 -314.21 6.32 11.89 0.35 F - ltt9239 2398029465700538880
66 LTT9491 23h19m35.650s -17d05m28.306s 349.89854 -17.09120 242.14 10.40 39.16 14.08 -0.04 DC - ltt9491 2405805697263561600
67 Feige110 23h19m58.391s -05d09m56.182s 349.99329 -5.16561 -8.37 -0.63 3.73 11.79 -0.24 DOp - feige110 2633603478379307904
68 GD248 23h26m06.542s +16d00m17.492s 351.52726 16.00486 -41.52 -115.57 29.50 15.08 -0.01 DC - gd248 2814629409239942272
No. Name RA Dec (epoch 2015.5) RA, deg Dec, deg pm_RA, mas/yr pm_Dec, mas/yr parallax, mas g mag B-g, color SpecType Note ESO webpage Gaia ID

Notes (from original ESO table): Stars with "Model" in the Notes column only have model data for the optical (3300-10000A) range and should NOT be used for flux calibration over this range. Bohlin & Lindler (1992) gives more details.


A special note for MMT observers

The legacy MMT catalog tool used with Blue/Red Channel spectrographs does not take proper motions in milli-arcsec per year, but rather in pm_RA = seconds of time per century and pm_Dec = seconds of arc per century. These differ from the mas/yr values:

pm_RA (sec of time/century) = pm_RA(mas/yr) / [10 * 15 * cos(Dec)]

pm_Dec (sec of arc/century) = pm_Dec(mas/yr) / 10
Also, the catalog tool for Blue/Red Channel only accepts epoch 2000 coordinates, not epoch 2015.5, so you should back propagate the coordinates to epoch 2000. An issue with this catalog tool is that it will use the same number for epoch and equinox, so if you want to apply proper motions you should do one of two things: If you are working with some other catalog that properly handles epoch and equinox separately, you don't have to worry about this.

The MMT queue observing interface used with MMIRS and Binospec requires the same funky per-century units, and is intended to allow input of different epochs, but we have had the same epoch=equinox issue in some internal software, so you are safer advancing the RA/Dec coordinates to the current time as described above.


Questions? Please contact Benjamin Weiner, bjw @ mmto.org.

This page uses data compiled and released by the Gaia mission archive and the SIMBAD database of CDS, Strasbourg.

Page by Benjamin Weiner, MMT Observatory.


Last modified: Wed Feb 5 15:12:29 MST 2020