* GUIDE TO RECOVERY AND DISCOVERY WORK IN THE NEAT ARCHIVES (SKYMORPH)
* ASTROMETRICA and FINDORB *
by Marco Langbroek
* This guide was written after questions on how I work with NEAT data.
It is the way
I work (other ways are possible) and can be a guide to novice users of
Much of the technique described in this guide, I learned from Rob Matson,
heartfuly thank for his teaching!
* The guide focusses on the discovery of new objects in the NEAT archives,
serves as a guide to doing precovery work on known objects.
* It is assumed that the astrometric program
used is Herbert Raab's very fine shareware
"Astrometrica", see http://www.astrometrica.at
* Also needed is Bill Gray's freeware "FindOrb", http://www.projectpluto.com
* If you want to do this kind of work, you should get yourself acquainted
with the meaning
of orbital elements.
Note: Astrometrica has very good step-by-step tutorials in the "help"
section. Do these
tutorials to learn to work with the software.
Okay, here it goes step by step:
0. Go to Skymorph, http://skys.gsfc.nasa.gov/skymorph/skymorph.html and
for images by time and position". Fill in a position (both RA and
be input in degrees) and time search definition. Tip: mid-August 2002
has a number of
good quality nights close together.
*For precovery work, omit this first "step zero", go to step
8 immediately and omit
step 5. At step 8b, fill in the object designation at the top of the page
orbital elements below if it is a very recent discovery not yet in the
1. Download triplet of 3 FITS files with about 20-30 minute time spacing
FITS from station 644 have an a, b or c behind the image number, the other
from station 608. The 608 images have so many false artifacts (and worse
magnitude) that I never use them for searching, only for additional positions
a find. I usually download images of 1100 x 1100 pixels (you can set this
downloading under "request parameters: NEAT pixels". Also un-tag
"NEAT/DSS SkyView overlay" as you won't need these)
2. Open them in Astrometrica (and type in image dates and time in the
that appear); Make sure your configuration file used is the 644.cfg (you
alter this through "settings"), an example of which can be found
3. Make a blink of these 3 images (tools ---> blink image, or click
4. Look by eye for moving objects (Rob and I never use the auto-detect
when you have one, check whether the movement is consistent with the image
5. If you have a moving object, check whether its a known asteroid or
not using ASTPLOT:
*note*: the reason for using ASTPLOT and not the "known image overlay"
Astrometrca itself, is that the MPCORB file Astrometrica uses will be
for the current
epoch and not the epoch of these "old" images, which will introduce
5a. Select the correct station code from the list in Astplot, fill in
date, time and
image center of the middle image of the triplet, change limiting magnitude
+21.5 and image vector to "1 hour" and then click "obtain
5b. It takes a while, but after some 2 minutes or so it will generate
Compare this map to your images.
6. If the object on your images is an unknown: measure 3 positions (3
6a: click "astrometry ---> data reduction";
6b: enter coordinates of image center (leave "object" field
6c: Astrometrica will now download the appropriate set of
reference stars from USNO-B1.0 catalogue over the internet;
6d: after downloading it will proceed to auto-match this set
to the stars in the images *This can take several minutes!*;
6e: After the fit to the stars has been achieved, click on the
object you want to measure in the (first of 3) image;
6f: Astrometrica will auto-match to the center of the object. If
you are satisfied with this fit (99 out of 100 times), enter
a preliminary designation of 6 characters (e.g. "YOU111") in
the most lower-right box (the right-most box under "object
designation": leave the left box blank) and then click "accept";
if you are not satisfied with the fit click "reject", zoom in
the image and mmanually put your cursor where you want it, then click
while holding the "ctrl"-key;
*Note*: if the object you measure is not a new discovery but a precovery,
enter it's "packed" MPC designation in the lower right box;
6g: Repeat steps 6e and 6f for the other two images.
6h: Astrometrica will auto-write each measurement to the file MPCReport.txt
in the correct MPC report format;
6i: *Note*: when starting up Astrometrica, it may say "MPCReport
exists" and asks whether you want to overwrite it. DON'T DO THIS!
will loose all previous measurements in the file... Periodically
archive MPCReport.txt by renaming it and then let Astrometrica create
a new, blank one. Note that new measurements on new objects are appended
the existing MPCReport file, it will not overwrite older data in the file.
Your first set of measurements is now ready! This was the easy part.
Now comes the
You now have to find the object back on images of at least two other
nights, one of
which must be close to the first night (e.g. no more than a week later,
less...). For this, you have to "predict" where to look...
7. Switch to FindOrb software (www.projectpluto.com),
which is an orbital propagator.
FindOrb will try to calculate a very preliminary orbit from a set of measurements.
It reads files in MPC format so it can directly read the file MPCReport.txt
7a: start-up FindOrb and open the file "MPCReport.txt" (which
find in C:/Program Files/Astrometrica);
7b: you will see a list of all objects in the file. Click on the name
object you want to process;
7c: you will now see a preliminary set of orbital element;
7d: fill in a value for the perihelion distance which is sensible for
main belter in box "R1";
7e: click "Vaisala";
7f: You will now get a set of estimated orbital elements, and an
indication of the fit of the observations to this estimate.
*note 1* a Vaisala orbit is an orbit based on the assumption that
the object is in perihelion.
*note 2* you need to have some knowledge of orbital elements to
judge whether the FindOrb results make sense (they don't always do).
8. Now go back to the Skymorph website and:
8a: Choose "moving targets".
8b: scroll down and enter the orbital elements obtained by FindOrb into
the data input boxes, then click "send"
9. Skymorph will now return a list of images which *might* contain the
based on the preliminary orbit you submitted. This list should include
triplet of images which you measured, otherwise there is a mistake in
the data input.
10. Go back to step 1, and this time use a second night as close to your
first one as
possible: repeat the whole sequence up to step 4;
11. Now you will either find an object of correct magnitude *and moving
in the correct
direction* in the set of images, or you won't. This is the hard part.
simply do not find the object. Bad luck then. Note that the object need
not be in the
image center, it only will be if the preliminary orbit obtained by FindOrb
is a quite
12. If you are lucky and do recover the object: repeat the whole sequence
up to step 7c;
13. After step 7c, this time check all planets for nclusion of their
disturbing factors,and then click "Autosolve" instead of "Vaisala".
You will get a new set of improved orbital elements.
Take a carefull look now at your residuals. These should be below 1.0
for each data line. When they are (much) bigger, this is an indication
is wrong: for example that the object of the second night is *not the
same* as that of
the first night (this is very well possible!)! Or maybe something went
wrong when measuring an image. In this case, do *not* proceed to step
14. You will now have a new set of improved orbital elements. Go back
to step 8 and repeat. Try to do this again and again untill you have data
from as many nights as possible. You'll also notice that the orbital solution
will get better and better, and after 3-4 nights of data you'll start
to recover your object in the center of the images.
At some point now, you'll not be able to get more nights. If you have
at least 3 nights
including two that are close together (within a week), you can submit
your data to the MPC now (in the case of recovery of a known object instead
of discovery, you can report single night data).
15. *BEFORE* you start to submit data to the MPC, carefully read their
http://cfa-www.harvard.edu/iau/info/ObsFormat.html ! I also advise to
16. Astrometrica already formats the data in the correct MPC format.
Copy and paste the
data you want to sent from MPCReport.txt (which is in C:/program files/Astrometrica)
into a blank e-mail making sure you maintain the correct format (i.e.,
spaces, indentation etc.) and *include the correct header details*. Send
*Note* sent the e-mail as plain txt, *not* HTML, and remove any signatures
from the mail.
A typical, correctly formatted e-mail with data and correct header will
CON *your name and address*你的姓名和地址
CON *your e-mail in square brackets  *用方括号括起来的你的Email地址
OBS R. Bambery, E. Helin, S. Pravdo, M. Hicks, K. Lawrence, R. Thicksten
MEA *your name*你的名字
TEL 1.2-m Schmidt + CCD
ACK *fill in a code or whatever that identifies this set for you*你的代号或你认可的身份标识
LAMA90 C2002 08 08.44720 22 18 41.93 -13 37 36.8 20.7 R 644
LAMA90 C2002 08 08.45810 22 18 41.35 -13 37 37.6 20.8 R 644
LAMA90 C2002 08 08.46909 22 18 40.75 -13 37 40.0 20.6 R 644
LAMA90 C2002 08 18.42448 22 09 15.73 -14 02 21.6 20.7 R 644
LAMA90 C2002 08 18.43537 22 09 15.09 -14 02 22.8 19.4 R 644
LAMA90 C2002 08 18.44572 22 09 14.47 -14 02 24.7 20.1 R 644
LAMA90 C2002 08 26.17449 22 01 26.68 -14 20 27.2 20.7 R 644
LAMA90 C2002 08 26.24252 22 01 22.42 -14 20 36.8 19.9 R 644
LAMA90 C2002 08 26.31396 22 01 17.94 -14 20 45.6 20.2 R 644
LAMA90* C2002 08 29.36705 21 58 14.54 -14 26 57.7 19.8 R 644
LAMA90 C2002 08 29.38826 21 58 13.20 -14 27 00.2 20.1 R 644
LAMA90 C2002 08 29.41086 21 58 11.81 -14 27 02.7 20.6 R 644
In the above example (which is data I submitted for a new object that
based on this
dataset got the official MPC designation K02Q66R), "LAMA90"
is a preliminary personal
designation for the object. Use your own 6-digit personal designation
*Do not call your designations "LAMAxx" but design your own
"LAMAxx" is my personal system of temporary designations for
Under "ACK", fill in for example your personal object(s) designation(s)
dataset (see point 17).
17. After receipt of your e-mail, MPC will within a few minutes automatically
an acknowledgement, which will have as subject line the line you specified
18. After some time (a few hours or up to a few days, this depends) someone
at the MPC
will sent you a mail called "designations". You will see a line
with your temporary
designation, followed by the official designation assigned by the MPC.
This of course,
assuming the MPC accepts your report. To understand the meaning of the
of this message, read http://cfa-www.harvard.edu/iau/info/Astrometry.html#des
19. The next day after MPC mailed you the designation, you'll probably
find it listed in
the Daily Orbit Update (DOU). You can find these at
20. You can check whether the object has additional single night observations
stations linked to it at http://cfa-www.harvard.edu/iau/MPEph/MPEph.html
fill in the packed designation, check "MPC 8 line" format and
check the "show
residuals" block and then click "get ephemerides"
* NOTE * After recent MPC policy changes, you will no longer get official
credit for new
objects for which a previous single night report exists. Credit instead
will go formally
to NEAT or the other station that sent in the single night detection.
This is a bit of a disappointent after your hard work in prying out all
undiscovered detections from the archive but then, that's the way it is.
hunters now count their finds unofficially as 'discoveries' just as SOHO
comet hunters do.
Okay, hope this helps!!!! Happy hunting!
- Marco Langbroek
Note 1: My sincere thanks to Rob Matson, who introduced me to the wonderful
of SKYMORPH precovery and discovery. Almost all of the things this guide
contains, I learned from him.
Note 2: if you mirror this guide, please acknowledge the source
Dr Marco Langbroek
Leiden, The Netherlands
Volunteer image reviewer FMO Spacewatch Project
NEAT archive hunter
Admin FMO Mailing List
private website http://home.wanadoo.nl/marco.langbroek/asteroid.html
FMO Mailing List website: http://home.wanadoo.nl/marco.langbroek/fmo.html
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