Benjamin Weiner, MMT Observatory
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.
If you are looking for standards for observations with the MMT, please note that the legacy MMT catalog format uses non-standard units for proper motions. You must read the note for MMT observers at the bottom of the page.
If you don't want to worry about proper motions, choose a standard star that has very small proper motions, less than about 30-50 mas/yr. For a large telescope you should use a star fainter than magnitude 10 or so. Some good stars are: HILT600, GD108, Feige34, Feige66, Feige67, BD+33d2642, Feige110. If you use one of these stars, you shouldn't need to enter proper motions for the next century or so.
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. 2022.8. 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).
| 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.
The legacy MMT catalog tool used with Blue/Red Channel spectrographs, and the MMT queue catalog for Binospec and MMIRS, does not take proper motions in units of 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) / 10Also, the catalog tools for Blue/Red Channel and Binospec/MMIRS default to epoch/equinox 2000 coordinates, not epoch 2015.5. The MMT mount code unfortunately sets equinox=epoch (which is wrong), so that if you enter a non-2000 epoch it will precess the coordinates, which is undesirable. We are working on modifying the MMT mount code so that it only uses equinox J2000 (ICRS) reference frame, allowing epoch to be useful, but it's not there yet. So if you want to use a star that may have significant proper motions, you can do one of three things:
The MMT queue observing interface used with MMIRS and Binospec requires the same funky sec-per-century units, and allows input of different epochs, so you need to follow the procedure 1 or 2 above to enter the star position. This is especially important for Binospec because it doesn't have a slit viewing camera, so if your star is even a few arcsec off, it won't be acquired.
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.