July 2001 - monthly monitor

Highlights from the month

The present summary includes activities and results conducted from June 10 to July 8, 2001. A total of 18 NEOs were discovered, 16 single-opposition targets were recovered and a few more interesting observations were made.

None among the newly discovered NEAs seems to be particularly hazardous for the Earth in the near future.

NEO discoveries of the month

This month 17 new NEAs were discovered by 3 observing programs: 8 by LINEAR (code 704), 7 by PALOMAR-NEAT (644), and 2 by LONEOS. While some of the discovery programs have suffered from cloudy weather especially during the second half of the lunation, PALOMAR-NEAT has confirmed the great potential of the system thanks also to nice weather conditions, pretty common in southern California during the summer.

As for the cometary component of NEOs, one such comet was discovered, among those with a perielion distance < 1.3 AU, bringing the total number of discoveries of the month to 18. This comet, designated P/2001 MD7 (LINEAR), has a revolution period of 7.50 years, and has a typical orbit of a short-period comet.

In the following table, the first column reports the provisional designation assigned by the MPC to the new object, the second shows the MPC code of the discovery site and the third reports the follow-up status of the object. This is indicated by a letter which corresponds to a specific interval of values of the object MUR.


 Object    MPC code   Follow-up status (see explanations)



2001 LL5   -  644  -    V
2001 LM5   -  644  -     W
2001 MF1   -  699  -      X
2001 LD6   -  704  -  T
2001 ME1   -  704  -       Y
2001 MD1   -  704  -   U
2001 LE6   -  644  -      X
2001 MG1   -  644  -  T
2001 LO7   -  704  -     W
2001 MQ3   -  644  -  T
2001 MR3   -  704  -   U
2001 MS3   -  644  -  T
2001 MY7   -  704  -  T
2001 MZ7   -  704  -       Y
2001 MA8   -  644  -  T
2001 MT18  -  699  -    V
2001 MK3   -  704  -   U



where

- T is given for  MUR > 20.0
- U is given for  5.0 < MUR < 20.0
- V is given for  1.0 < MUR <  5.0
- W is given for  0.3 < MUR <  1.0
- X is given for  0.1 < MUR <  0.3
- Y is given for  MUR <  0.1

A list of the MUR status for all NEAs is available here. It has been made available according to this nomenclature and it does not include numbered objects.

Additional notes:

- 2001 MS3 a small NEA (about 100 meter in size) was discovered a few days after a close encounter with the Earth at 0.025 AU.

- 2001 LO7 and 2001 MZ7 are rather large NEAs, with sizes around 3 to 5 km. 2001 LO7, which shows a very large eccentricity was discovered in the outer side of the main-belt region.

NEO follow-up observations

Follow-up efforts have been pretty successful during the past lunation. They have concentrated towards the recovery of single apparition targets while only a few objects in urgent need of observations were followed in the course of the discovery apparition.

The following sections provide more details on these results.

Critical observations of NEOs in urgent need of observations

The following list is a summary of critical observations, made when these targets were flagged as a Urgent in the Priority List


     Object      Obs. type   observatory code  (MPC)


2001 KD68  -    UR      -  691
2001 MG1   -    UR      -  046, 360, 649
2001 MS3   -    UR      -  671, 649, 422
2001 BO60  -    UR      -  413(1)
2001 BF10  -  UR + SP   -  807
2001 KO20  -    UR      -  413(1)
2000 KO41  -    UR      -  413(1)
2001 KY66  -    UR      -  413(1)
2001 LL5   -    UR      -  413(1)
2001 ME1   -    UR      -  413(1)
2001 MY7   -    UR      -  413(1)

SC = special campaign directly coordinated by the Spaceguard Central Node

UR = Targets listed as urgent at the time of observation, either in the Priority List or in the Faint NEO List.

radar = radar observations

FNL = targets reported as Necessary on the Faint NEO List or made under special conditions, beyond the threshold of the FNL. For example, observations of faint targets made at small solar elongations (SSE).

The number in parenthesis next to some observatory codes indicates the team that was observing from that observing site, according to the MPC nomenclature.

Missing observations of targets in urgent need of observations

We briefly summarize a list of NEOs insufficiently observed, which terminated their visibility apparition during this monthly period, according to this plot. These objects, recently reported in urgent need of observations, should be now considered lost because of insufficient follow-up and/or because of the intrinsic limits of optical astrometry. Next to the target designation we have reported its absolute magnitude.


2001 KW18  - (H = 26.0)

NEO recoveries of the month

In the past month, 16 NEOs have been added to the list of multiple-opposition list. The great bulk of this effort was provided by DANEOPS in the form of targeted searches with a 1.5-m reflector at Calar Alto Observatory in Spain. Six NEOs were precovered on photographic archives, mostly by DANEOPS and by R.H. McNaught. No identifications on pre-existing data or accidental recoveries were made during this lunation.

In the following scheme we report the object designation, the kind of recovery and the observatory codes involved in the observations.


  Object     Type   Observatory code (MPC)
                                                                
1999 YA     - R -  540, 493
1998 HL1    - R -  493
1999 MM     - R -  493
2000 FL10   - R -  493
1999 CV8    - R -  493
1999 RL45   - R -  493
2000 OK8    - R -  493
1999 TN12   - R -  493
2000 LB16   - R -  493
1999 PJ1    - R -  413
2001 FM129  - P -  260(1)
1998 TX6    - P -  261(2)
2001 LF     - P -  261(1)
2000 QU7    - P -  413(1)
2000 YN29   - P -  413(1)
2001 MZ7    - P -  260(1), 413(1), 261(1)


R indicates a targeted recovery at the telescope
P indicates a precovery on some archival collection
I indicates an identification from pre-existing observations
A indicates an accidental recovery at the telescope

Further notes:

Missing Recoveries

We report a list of single opposition NEAs that have not been recovered during the current apparition, and ended their visibility during this monthly period, according to this plot:


1998 KD3
1999 GT3
1999 TA10
2000 EF104
1998 MZ

These targets were recently listed in the Recovery and Bright Lost NEOs services during the past recovery opportunity.

Summary of special campaigns

During this monthly period further observations of 2001 BF10 were reported by a team working with TNOs from Cerro Tololo. Although the observing campaign of this object was terminated with the availability of radar observations during the past lunation, the new data has been still very useful and would have been mentioned in the closing announcement if reported earlier to the MPC and SCN.

There are no NEOs under special surveillance at the moment. Around July 24th, a relatively small Aten, 2000 PH5, is expected to have a very close encounter with the Earth at 0.010 AU. Radar observation may take place on July 27, 28 if a recovery is made before the radar opportunity: in fact, the sky uncertainty of 2000 PH5 will be of many degrees.

For more information or short-term changes, please keep looking at the section related to Special Campaigns, or directly on the New Announcement list or, if solved, on the list of Successful campaigns.

Sky coverage summary of the big surveys

This month there was a significant decrease of the number of discoveries respect to the previous lunation because the search activity was significantly reduced during the second half of the lunation. Nevertheless, it is not clear exactly how much was the total sky coverage operated by the big surveys since there is still no information about the work done with the Palomar-NEAT system. No NEO searching could be performed on five nights concentrated near full Moon: June 26, July 1, 6, 7 and 8.

These comments and sky coverage analysis are based on sky coverage plots available at the Lowell Observatory and the Minor Planet Center.

Sky Coverage at very northern declinations, from +50 to +90:

- extensive coverage by LINEAR on June 11; about half of the celestial sphere between +50 and +80 was covered. A comparable amount of sky coverage was made by LONEOS, combining efforts from June 10, 16, 17, 18, 20 and 30.

Sky coverage at high northern declinations followed the general trend of this lunation, with very limited or no activity after new moon.
One problem that is not solved yet is that about half of this region at high northen latitudes, the one centered on solar conjunction, is not covered even once per month.
No sky coverage was made between +80 and +90 deg.
NO Sky Coverage was performed South of -35 deg.:

Because of this problem, as well as the lack of a complete coverage at high northern declinations, the current status of NEO sky coverage cannot be considered an all-sky survey.

Coverage within +/- 10 degrees from the ecliptic was very satisfactory from all the active surveys if we consider solar elongations greater than about 80 degrees. The Spacewatch program gave also a significant contribution at fainter magnitudes, although its sky coverage is more limited. NEAT provided the great bulk of the activity during the second half of the month.
Coverage between 10 and 50 degrees from the ecliptic:

Sky coverage between 10 and 30 degrees has been very satisfactory North of the ecliptic during the first half of the lunation, but not so extensive on the southern side, especially because part of this region is located South of the -30 deg. declination limit.
Further regions, located between 30 and 50 degrees from the ecliptic, have also been covered pretty satisfactory during the second half of the lunation. The main contribution was provided by LINEAR on June 13, 14, 17 and 18 while a quite regular contribution was provided by LONEOS, on June 11, 12, 14, 15, 16 and 19. NEAT took over in this region of the sky towards the end of the lunation.
Searches at small solar elongations:

The most disappointing aspect of the search efforts in this month was, essentially, the total absence of NEO searching at small solar elongations Only NEAT covered an area in the evening sky at 70-75 deg. of elongation on June 30.

NEA size distribution

The following plot shows the NEA size distribution as of July 8, 2001. It comprises a total of 1395 bodies. Actually, there are two overlapping histograms, the orange bins report the number of NEA discoveries of the previous month (until June 9, 2001), while the black contours show the total NEA size distribution as of this month.

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This document was prepared on July 19, 2001, by Andrea Boattini and Germano D'Abramo