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Wednesday 9 April 2008
Today, we have implemented a new roster of perturbers in our integration
scheme. Previously, the perturbers were Mercury through Pluto (Eath and Moon
separately) plus 1 Ceres, 2 Pallas, and 4 Vesta. We have now added
perturbations from 10 Hygiea, 15 Eunomia, 52 Europa, 511 Davida, and 704
Interamnia. Most of the asteroid masses have been adopted from JPL's DE-405
ephemeris.
Wednesday 9 April 2008
The switch to the new server is partially complete. Our software appears to
run correctly on the new server, but WWW URLs do not work. Please be patient
while we try to fix the web interfaces, a nontrivial task.
Tuesday 1 April 2008
Today, we will switch to a new server. Therefore, our asteroid services URLs
will be down for a while---perhaps for as much as a day or two. We will issue
an "all clear" when services appear to have been restored.
Saturday 12 May 2007
Several coorespondents have recently pointed out errors in asteroid absolute
magnitudes (H). Larry Wasserman and I (Ted Bowell) have identified a couple of
coding errors that have led to the problem, and I have recomputed H values
(and orbits) for the offending asteroids---about 3000 of them. Please let me
know if you spot any more errors in H values.
Friday 3 September 2004
The problem mentioned on Wednesday 25 August has been dealt with.
Wednesday 25 August 2004
We have corrected a small error in the computation of the
geocentric-to-topocentric positions of asteroids. The correction affects
orbits and ephemerides (using our software) computed on or before Tuesday 24
August 2004. The correction is generally small (< 0.01 arcsec in ephemerides),
except for some Earth-approaching asteroids, where it may amount to several
tenths of an arcsecond. We will be recomputing orbits for the affected NEAs in
the near future.
Thursday 12 February 2004
The problem reported on Monday 9 February appears to have been corrected.
Monday 9 February 2004
The corruption problem should have been corrected, though we will be
monitoring the orbit files for a few days to verify. Full daily updates should
now proceed as normal, beginning tomorrow morning.
Monday 9 February 2004
Corruption of two asteroid orbital element files has occurred. Full daily
updates have been suspended pending correction.
Wednesday 3 July 2002
Full daily updates of astorb.dat have restarted following inclusion of data
from the 24 June 2002 Minor Planet Circulars. The shortcuts referred to in the
note of Monday 3 June 2002 will be applied till further notice.
Monday 3 June 2002
Full daily updates of astorb.dat will be resumed on Tuesday 4 June 2002 UT
following inclusion of data from the 26 May 2002 Minor Planet Circulars. Note
that we have taken some short cuts in the preparation of astorb.dat this
month. In particular, ephemeris and similar programs may not work for a while
for all asteroids if dates far from current are requested. Please let
ebowell@lowell.edu know of any problems you encounter.
Monday 17 December 2001
The problem noted on 25 November has now been fixed, and a new astorb.dat,
with related files, is available.
Tuesday 11 December 2001
The problem noted on 25 November has been isolated but not fixed. We expect it
will go away when data from the 30 November 2001 MPCs have been assimilated,
which should occur by this weekend.
Sunday 25 November 2001
One of the component programs of the nightly update of astorb.dat is hanging.
Unfortunately, I (Ted Bowell) and my knowledgeable colleagues are attending a
meeting in New Orleans, and we cannot fix the problem remotely. Expect a fix
in early December. Meanwhile, orbits from the daily MPECs are being
incorporated into astorb.dat as usual.
Tuesday 31 July 2001
Henceforth we will be including some MPC-published orbits in astorb.dat. On a
day-to-day basis, these will comprise MPEC orbits, and will be so identified
by the MPEC reference in the "orbit computer" field. During times of
transition, when MPC monthly update files have been published but orbits have
not been computed at Lowell, MPO orbits will be found in astorb.dat. The
presence of an MPEC or MPO orbit implies that it is preferred to the orbit we
can calculate at Lowell. This is because MPEC and MPO orbits are based on more
observations than are available to us. For the same reason, MPEC and MPO
orbits contain no ephemeris uncertainty data. Likewise, the arclengths of
multi-apparition MPEC and MPO orbits are guesstimates.
Friday 23 February 2001
The problem reported yesterday should now have been corrected.
Thursday 22 February 2001
We've been having a problem with one of the component programs of the
full nightly update procedure. (It's a program that generates a current
file of ephemerides, which, in turn, is used by utilities such as plast).
Should be fixed for tonight's run, which we hope, therefore, will
produce uncorrupted output.
Thursday 28 September 2000
Full daily updates of astorb.dat will be resumed on 29 September UT
following inclusion of data from the 13 September 2000 MPCs. We apologize
for the delay, which has been caused by file dimension problems (internal
files got too large for our operating system!). Please let us know if
you see any problems.
Sunday 6 August 2000
The residual problems with astorb.dat, noted on Thursday 3 August 2000,
have now been corrected.
Thursday 3 August 2000
Owing to lightning damage to part of Lowell Observatory's internal network,
we have been unable to complete the orbit database update today. A full
daily update will be carried out tonight, but users should note that there
will be known errors, such as a lack of new names for numbered asteroids,
that will persist for a day or two. Watch for an "all clear" message.
Monday 10 July 2000
The problem of the corruption of orbits by duplicate observations, reported
on Saturday 8 July, should now have been corrected.
Saturday 8 July 2000
Full daily updates have been resumed following inclusion of data from the
21 June 2000 Minor Planet Circulars. Due to the publication of the original
PLS, T1S, T2S, and T3S in those MPCs, and the way we process new
observational data, there are about 1000 orbits in astorb.dat that contain
duplicate observations (and have thus been slightly corrupted). Those orbits
will be recomputed soon.
Saturday 22 April 2000
From this date on, orbit computations will make use of perturbing body
ephemerides from DE-405. Old orbits, which use DE-403, will gradually be
replaced.
Thursday 20 January 2000
astorb.dat should be in good shape again (see the note of Monday 3
January). Thanks to Tiziano Magni and Zdenek Moravec for pointing out some
y2k bugs (we thought, in our innocence, that there would be few if any).
Please let Ted Bowell (ebowell@lowell.edu) know if you see any additional
bugs.
Monday 3 January 2000
Owing to my (Ted Bowell's) vacation, there will be no full updates of
astorb.dat till at least Friday 14 January 2000.
Saturday 25 September 1999
Most of the upgrade process, referred to on Friday 17 September, went
smoothly. One prolonged snag has been reinstituting full nightly updates of
astorb.dat. However, we think that all the Lowell asteroid services are
functioning normally. Let us know if you find otherwise.
Friday 17 September 1999
We will be upgrading our server for Lowell Observatory's asteroid services,
including the provision of astorb.dat, on Monday 20 September. We hope that
the process will take less than a day, but there may be snags... Also note
that asorb.dat will not be fully updated from tomorrow until at least
Wednesday 22 September.
Saturday 11 September 1999
Full nightly updates of astorb.dat will be resumed tonight following
incorporation of data from the 1999 August 31 MPCs. However, there may be
one or two strange bugs. We are working on them, but do let us know if you
find anything unusual with astorb.dat or the various asteroid services.
Tuesday 31 August 1999
Further to the note of Thursday 26 November 1998: Orbits hitherto uncomputable
due to a relatively new method of computing covariance matrices have now been
reinserted in astorb.dat following a change to our computational methods.
Mostly, the covariance matrices remain indeterminate, which results in
erroneous ephemeris uncertainties. The ephemeris uncertainties should,
however, be large, so users will be alerted that the objects affected cannot
easily be recovered.
Monday 5 July 1999
Peter Schlatter has pointed out that the high inclinations of 1999 LD31
and 1999 LE31---both larger than 100 deg---caused overflow in their records
in astorb.dat. The problem has been fixed with a format change, as also
noted in astorb.html.
Tuesday 4 May 1999
Mark Sykes has pointed out that asteroid diameters given in astorb.dat are
from a preliminary IRAS database. Accordingly, we have replaced them with
values from the final IRAS database, as provided by the Small Bodies Node
of the Planetary Data System.
Friday 2 April 1999
Peter Schlatter has pointed an error in the epoch of orbital elements in
astorb.dat: rather than being 19990502 it is 19990002. The error has now been
fixed, but users who have downloaded astorb.dat during the past three or four
days should check to see that the epoch is indeed 19990502. Otherwise they
should download astorb.dat again.
Monday 1 February 1999
The LONEOS web service failures referred to on Sunday 17 January should
now have been fixed.
Sunday 17 January 1999
Following the format change to astorb.dat (Thursday 31 December 1998),
certain LONEOS asteroid web services do not work: obs (asteroid
observability chart), astfinder (asteroid finder chart). The following
works for some asteroids and not others: astephem (asteroid ephemeris),
The underlying problems should be fixed over the coming days.
Friday 8 January 1999
We have modified the meanings of values of integer code 1. Specifically,
value = 1 now pertains to Aten asteroids, value = 2 to Apollos, and
value = 4 to Amors. Other values have been corrected where errors were
detected. For details, refer to the table of integer-code values in
astorb.html.
Wednesday 6 January 1999
We have heavily modified our "critical list" of asteroids in need of
astrometric observation. In particular, there are now two lists: one
containing all appropriate asteroids, the other containing just those that
come to opposition during the current lunation. Click on
here.
Thursday 31 December 1998
The format of astorb.dat has been changed in accordance with the remarks
(below) dated Saturday 26 December 1998. The text describing astorb.dat
(astorb.html, accessible from the web) has been modified to describe the
change.
Saturday 26 December 1998
We will be changing the format of astorb.dat to accommodate the impending
numbering of asteroids > 10000. The changeover, which will most likely occur
during Tuesday 29 through Thursday 31 December 1998, will comprise an extra
column at the left of each record. Stand by for further information.
Monday 7 December 1998
We are modifying the procedure for generating our critical list of
asteroids in need of astrometric observation. Things may go wrong in the
next few days, so please bear with us.
Thursday 26 November 1998
Our new method of computing covariance matrices (see note of Friday 9
October) results in some quasi-indeterminate orbits being rejected. The
objects concerned (and therefore missing from astorb.dat) are 1998 SM35,
1998 SL45, 1998 TN1, 1998 UZ14, 1998UD16, and 1998 UQ16.
Monday 9 November 1998
We have now more or less recovered from last Friday's disk crash. Please
report any oddities to ebowell@lowell.edu.
Saturday 7 November 1998
We've had a serious disk crash, which has affected astorb.dat. Efectively,
we are at present unable to do the daily updates, so the ephemeris
uncertainties and some integer codes are stale. We may not be able to resolve
the problems till next workweek.
Friday 9 October 1998
We have been improving the computation of ephemeris uncertainties. Data for
multiple-apparition asteroids should be largely unchanged, but ephemeris
uncertainties for many single-apparition asteroids will increase. We hope
that the new results will better reflect reality.
Tuesday 3 February 1998
Integer code 2:128 has been implemented. It pertains to asteroids that have
been sought but not found. Several possible reasons can be adduced: (1) Orbit
and/or current ephemeris uncertainty in error. (2) Search not deep enough.
(3) Asteroid image blended with that of a star. (4) Observer error.
Wednesday 24 December 1997
We have developed a "critical list" of asteroids, containing numbered
asteroids whose orbits are unsatisfactory or suspect and unnumbered asteroids
that are likely to be numberable after a modest astrometric effort. Start at
http://asteroid.lowell.edu.
Friday 12 December 1997
We think we have cleared up the problem mentioned yesterday. But, as usual,
please do not place much reliance on orbits and current ephemeris
uncertainties derived from small numbers of observations spanning short arcs.
Thursday 11 December 1997
Re the note on Monday 1 December: In changing our protocol for computing
covariance matrices, a problem has arisen that affects mainly short-arc,
single-apparition asteroids: a few CEUs and PEU10s have zero value. Clearly,
these are erroenous and should be ignored.
Monday 1 December 1997
We are making some major changes to the structure of some files that are used
to generate astorb.dat. The changes will be transparent to most users, except
that we will be inserting new orbital elements of numbered asteroids over the
next few days. These will show up in the *.add files. Most of the new elements
will differ very little, if at all, from those already in astorb.dat.
Thursday 23 October 1997
Re the note on Sunday 5 October 1997: P/1996N2 = 1979 OW7 has now been
numbered as an asteroid (7968). Therefore, the orbit for 1979 OW7 has been
deleted.
Sunday 5 October 1997
Seeing no reason why the Themis-family object P/1996 N2 = 1979 OW7 is not
classified as an asteroid, we have added an orbit for it to astorb.dat under
the designation 1979 OW7.
Monday 22 September 1997
Orbits of asteroids resulting from Hipparcos observations have been
incorporated in astorb.dat.
Tuesday 2 September 1997
The problem mentioned on 13 and 14 August should now have been solved.
Thursday 14 August 1997
The problem mentioned yesterday has recurred in today's automatic update of
astorb.dat. But now the symptoms are clear: affected are data for asteroids
whose ephemeris uncertainty parameters have become outdated, and are therefore
in need of recomputation. We are uncertain when the problem will be corrected,
but will try to put things to rights on a day-to-day basis for the next few
days.
Wednesday 13 August 1997
Yesterday, we made some changes to our internal asteroid files that are used
to create astorb.dat. After the daily automatic update, we noticed that
future ephemeris uncertainties and their dates of occurrence, along with
corresponding integer codes number 6, had been corrupted in the case of more
than 100 asteroids (both numbered and unnumbered---no obvious pattern).
Because of vacation time and upcoming travel, it is possible that we will not
be able to correct the problem till early September. It might be that the
corruption is cumulative (i.e., data for an additional hundred or more
asteroids will become corrupted each night), in which case users should be
aware that very large values of future ephemeris uncertainties
(+/- 10^15 arcsec, say) are erroneous. Also, note that we do not expect to
incorporate orbits deriving from the 18 August 1997 Minor Planet Circulars
until early September.
Monday 2 June 1997
The known errors in astorb.dat, referred to on Sunday 1 June 1997, have
been corrected.
Monday 2 June 1997
Ladislav Nemec has pointed out some typos in designations [for asteroids
(7196) and (7590)] and duplicate orbits [for 1997 EM6 and 1997 GR9]. These
errors have been corrected.
Monday 12 May 1997
Milos Tichy and Francois Ochsenbein have pointed out that, for some asteroids,
the second integer codes in astorb.dat have values of -128 or -126. These are
erroneous, and should be 64 or 66, respectively. Please contact
ebowell@lowell.edu if you notice a recurrence of the problem.
Tuesday 18 March 1997
Thanks to Albert Timashev, St. Petersburg, Russia, we have corrected 35
mis-spelled or missing asteroid names. We now believe the names of numbered
asteroids to be correct (less diacritical marks, of course). Please let us
know if you find additional errors. (Note that the principal preliminary
designations of numbered asteroids are entered by hand, so errors undoubtedly
exist among them.)
Saturday 1 March 1997
Owing to a procedural error, the file of deleted orbits created on 27 February
(970227.del) has been lost. To avoid duplication of orbits, users are urged to
download a new version of astorb.dat.
Tuesday 4 February 1997
Tim Spahr (University of Florida) has pointed out an error in the absolute
magnitude (H) of 1977 TD. Investigation revealed that a software bug, which
has apparently persisted for several months, caused values of H for unnumbered
asteroids not to be updated when new observations containing magnitude
estimates were incorporated in new orbits. Concerned users of astorb.dat are
urged to re-download the file.
Sunday 29 December 1996
The error remarked on Sunday 29 December 1996 has been corrected, so daily
updates have been resumed.
Friday 3 January 1997
The epoch of orbits in astorb.dat has been changed from 19961113 to 19970221.
Sunday 29 December 1996
Due to a change in operating system on one of our computers involved in the
daily automatic updating of astorb.dat, the compressed version of the file
(astorb.dat.gz) and the *.add files cannot be generated. As a temporary fix,
we will post current versions of astorb.dat (uncompressed). The fault may
persist for another week (that is, until year-end revelries have come to an
end).
Tuesday 3 December 1996
New values of magnitude parameters H and G for numbered asteroids have been
incorporated into astorb.dat in accordance with those in the 25 November 1996
Minor Planet Circulars.
Friday 11 October 1996
Some users have reported difficulty reading the absolute magnitude H because
of variable format (values such as 14, 14.5, 14.56). In FORTRAN, a fix is as
follows
CHARACTER*5 HCHAR
C--- At some point you read the data such that the 5 characters (at most
C--- DD.DD of the H value are in HCHAR, then proceed as follows:
IF(HCHAR(3:3).EQ.' ') HCHAR(3:3)='.'
READ(UNIT=HCHAR,FMT=1) HCOEF
1 FORMAT(F5.2)
Wednesday 9 October 1996
In response to users who have difficulty downloading the complete astorb.dat,
we are instituting a method of logging changes in the orbital elements
therein. Users will now find files such as yymmdd.add and yymmdd.del in our
public ftp area accessible from the WWW. These cover activities for the past
30 days. Thus, 961007.add comprises records for asteroids whose orbital
elements were either added to or replaced in astorb.dat on 7 October 1996;
and 960930.del contains records for asteroids whose orbits were deleted from
astorb.dat on 30 September 1996. Note the following: (1) The *.add files are
refreshed every day. Thus, an orbit that was replaced on, say, 961001 and then
again on 961002 will have been found only in the 961002.add file on or after
the latter date. (2) The *.add files reflect changes in orbital elements only.
Changes to other parameters (such as H, G, and integer codes), as well as
daily updates of ephemeris uncertainties, are not reported in the *.add files.
Users who are interested in the latter will need to download the entire
astorb.dat.
Monday 7 October 1996
Along with automating the routine daily updating of astorb.dat, we are now
updating the computation of the minimum orbital intersection distances (MOIDs)
for planet-approaching asteroids. They are available starting at
http://www.lowell.edu/users/elgb/moid.html.
Thursday 3 October 1996
We have automated the routine daily updating of astorb.dat. The update will
start at 08:00 UT, and should take about 1 hour. It consists of: (1)
Recomputing current ephemeris uncertainties of date; (2) Recomputing peak
ephemeris uncertainties that have "expired" (that is, have peaks at past
dates); (3) Recomputing integer codes; (4) Transferring updated files to the
publicly accessible ftp area for access via ftp or the WWW. The files will be
unavailable during step (4), which should take a few minutes at about 09:00
UT.
Thursday 22 August 1996
To solve the problem encountered on 17 August (q.v.), the format for semimajor
axis has been changed from F11.8 to F12.8, with the result that the length of
records in astorb.dat has increased from 264 to 265 columns. See astorb.html
or astorb.txt for new record examples and FORTRAN format statement.
Saturday 17 August 1996
The semimajor axis of 1996 PW overflows the available field size, being more
than 100 AU. The value should be a = 141.3007235273188 AU. The error will be
corrected in a day or two.
Sunday 11 August 1996
All DE205 orbits have now been recomputed and replaced by DE403 orbits
(see note of 15 November 1995).
Friday 14 June 1996
The errors in PEU10, remarked on Thursday 30 May, have largely been
corrected. A few errors may remain, due to corruption of our observational
database. We will be checking the database next week.
Tuesday 11 June 1996
Asteroids having unknown absolute magnitude H (about 200 of them) have been
flagged by setting integer code 2 = integer code 2 + 64. H has been set to
14 mag (a guess).
Friday 31 May 1996
Values of integer code 6 (see astorb.html) have been redefined. The new
definitions will be given in astorb.html.
Thursday 30 May 1996
The error in CEUs, remarked on Tuesday 7 May, should have been corrected.
However, a new error, in which the 10-year peak ephemeris uncertainties
(PEU10) of some well-observed unnumbered asteroids are much larger than they
should be, has come to light. We hope to correct this latter error within a
few days.
Tuesday 7 May 1996
An error has been detected in the method of computing current ephemeris
uncertainties (CEUs) for 3-observation asteroid orbits in astorb.dat. The
error, which has persisted since the provision of CEUs on 16 April 1996, leads
to grossly underestimated CEUs. We are working on a fix.
Tuesday 16 April 1996
Ephemeris uncertainty parameters have been incorporated in astorb.dat. See
astorb.html or astorb.txt for details of the resulting format change and for
notes on applications of the uncertainty parameters.
Tuesday 2 Aril 1996
Most orbits having assumed eccentricities (integer code 2:2) have been
recomputed.
Saturday 30 March 1996
A software improvement has resulted in (statistically) more reliable
assumed-eccentricity orbits computed on and after this date.
Friday 8 March 1996
Brian Marsden, Director of the Minor Planet Center, has recently discontinued
the availability of batches of astrometric observations of asteroids and
comets in conjunction with the monthly publication of the Minor Planet
Circulars (though observations of individual asteroids are still available as
previously to those who subscribe to the MPC's extended computer service).
Consequently, we will not, until further notice, be able to acquire the
observations published in the MPCs very rapidly, and will not be able to update
astorb.dat soon after publication of the MPCs.
Wednesday 14 February 1996
The format of records in astorb.dat has been changed.
Wednesday 15 November 1995
The planetary ephemeris used to compute asteroids was switched from DE245 to
DE403. DE245 orbits will gradually be replaced by DE403 orbits.
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