4 January 2001 --

Week 256 results (2000 December 22 - 28)

• Her X-1 has returned to a low state (< 10 mCrab) as expected
• KS 1947+300 - rose to nearly 50 mCrab

29 December, 2000 --

Week 255 results (2000 December 15 - 21)

• RX J0146.9+6121 - does not appear to be detected in this week's results, so last week's note is not confirmed
• NGC 1851 (glob. cluster) - the source in this cluster is up to ~13 mCrab
• 4U 1608-522 - three 90 s measurements (all that we have obtained for several weeks) indicate a flux of ~350 mCrab
• Her X-1 - another main high on state is apparent with strength reaching ~80 mCrab
• KS 1947+300 - continued to maintain a strength of ~30 mCrab
• Cyg X-1 - remained active with flux up to ~1.2 Crab
• Cyg X-3 - becoming active with daily average flux up to ~260 mCrab

18 December, 2000 --

Week 254 results (2000 December 8 - 14)

• RX J0146.9+6121 - may be up to ~7 mCrab
• Mkn 421 - still pretty strong at ~15 mCrab
• Cen X-3 - returned to a moderately strong (up to ~250 mCrab) mode after a month of weak X-ray flux
• KS 1947+300 - up to ~30 mCrab
• Cyg X-1 - moderately active, up to ~ 1 Crab in 90 s averages

Note: Monitoring of Galactic center sources will be sporadic for the next month or so as the sun appears to cross that region of the sky.

11 December, 2000 --

Week 253 results (2000 December 1 - 7)

• Cir X-1 - the 16.6 day cycle has a profile that is sawtooth-like.
• 3A 1942+274 - may be above 20 mCrab again (but data is noisy)
• KS 1947+300 - may be up to 10 mCrab (also noisy data)
• 1ES 1959+650 - may be ~10 mCrab
• BL 2005-489 - perhaps ~13 mCrab

4 December, 2000 --

Week 252 results (2000 November 24 - 30)

• NGC 2024 (Orion molecular cloud) - appears to be up to 10 mCrab
• Mkn 421 - continues to be very strong at ~20 mCrab
• X1145-616 - up to ~15 mCrab
• KS 1947+300 - definitely below 10 mCrab

27 November, 2000 --

Week 251 results (2000 November 17 - 23)

• LMC X-3 - up to ~50 mCrab
• Mkn 421 - still near 20 mCrab
• 4U 1630-47 - seen to vary in the range 0.4 to 0.6 Crab
• CTB 33 (SGR 1627-41) - up to 0.5 Crab (We suspect Solar contamination or cross-talk from 4U 1630-47, which is only ~0.5 deg from CTB33, as the cause of the enhanced ASM count rate.)
• Her X-1 - declining from peak of "main on" state
• X1702-429 - below 10 mCrab in contrast to its recent flux of ~30 mCrab
• GX 1+4 - stronger than usual at ~40 mCrab
• X 1730-333 (Rapid Burster) - down to below 10 mCrab
• Aql X-1 - has returned to a quiescent state (<10 mCrab)
• KS 1947+300 - has weakened somewhat and is now ~8 mCrab
• Cyg X-1 - generally declined but was still stronger than in the typical quiescent state

20 November, 2000 --

Week 250 results (2000 November 10 - 16)

• Mkn 421 - up to ~20 mCrab
• 4U 1630-47 - up to ~0.5 Crab
• Her X-1 - up to ~50 mCrab as part of a new high state in the regular 35 d cycle
• X1730-333 (Rapid Burster) - outburst is ending, < 20 mCrab
• Aql X-1 - declined rapidly to ~70 mCrab
• GRS 1915+105 - highly active with 90 s average intensities from 0.5 to > 3 Crab
• KS 1947+300 - around 13 mCrab
• Cyg X-1 - fluctuated around 0.7 Crab

16 November, 2000 --

Weeks 248-249 results (2000 October 27 - November 9)

• UX Ari - showed a short (~1 day) flare to ~40 mCrab on MJD 51,850
• LMC X-3 - increased in strength to ~45 mCrab
• 4U 1630-47 - rises at the end of the time interval to ~65 mCrab
• X1730-333 (Rapid Burster) - is in outburst again; individual dwells showed intensities as high as 700 mCrab while daily averages were as high as 75 mCrab
• Aql X-1 - gradually declined to ~250 mCrab
• GRS 1915+105 - showed both highly variable and relatively constant states with the variable state intensity ranging from 0.5 to above 2 Crab
• KS 1947+300 - rose to ~13 mCrab (to the highest intensity seen yet by the ASM)
• Cyg X-1 - was strong and active with individaul dwells ranging up to ~2 Crab
• Cyg X-3 - declined sharply so that the later daily averages were typically ~100 mCrab

Notice: We are working on software that can facilitate analysis and display of ASM light curves. The S/W includes a package of C functions that can be used in main routines, a limited set of main routines that run a limited set of the package of functions, and a set of Supermongo macros for display purposes. The C functions are intended to perform tasks such as reading and writing files and memory allocation, filtering, barycenter and pulsar orbital time corrections, binning, phase selection (which can be used to, e.g., remove eclipses), and folding. To inquire about receiving the current developmental version of the software, please send a message to aml@space.mit.edu.

30 October, 2000 --

Week 247 results (2000 October 20 - 26)

• X 1730-333 (Rapid Burster) - Showed one 90 s measurement above 200 mCrab (but additional data from week 248 show that this is definitely another outburst)
• EXO 1745-248 - < 25 mCrab
• SAX J1747.0-2853 - may be a bit stronger than usual at ~40 mCrab (but the record is not entirely convincing)
• Aql X-1 - still mostly near ~500 mCrab
• Cyg X-1 - active with a flare to ~1 Crab (Note: This trend continues into week 248 which suggests the possibility that a high soft state is being approached.)

27 October, 2000 --

Week 246 results (2000 October 13 - 19)

• 4U 0115+63 - down to < 10 mCrab
• Her X-1 - intensity was as high as ~80 mCrab, which is a typical flux during the high state. A short (~1 day) interval of low intensity was seen between times of relatively high flux. The extended interval of more than one year with low flux has thus clearly ended.
• Aql X-1 - remained above 500 mCrab

Note: For this week, the files on the MIT web site and elsewhere containing the results for each dwell (i.e., *.dat files) have been revised from 12 to 13 columns. This will not affect anything in FITS files (yet) or upstream of light curves (e.g. solutions files). The 13th column contains the fitted count rate of the A-band diffuse background which is often a good indicator of contamination from solar X-rays scattered off Earth's atmosphere or the collimator, and can be used to flag suspicious points. ANY dwells with xbg_A > 40.0 will be eliminated from the ASCII light curves (too high!). For faint sources, we advise selecting xbg_A < 10. Normal values are distributed in the range 4.6 +- 2.1 c/s, with a typical uncertainty per dwell of 0.4 c/s. Users' personal programs that begin with ASM ASCII light curves may need to be modified.

16 October, 2000 --

Week 245 results (2000 October 6 - 12)

• 4U 0115+63 - down to ~13 mCrab
• Cen X-3 - is becoming bright again, as it is up to ~130 mCrab
• Her X-1 - appears to have "turned on" briefly. This confirms the weak and brief turnons seen 35 and 70 days previous to this turnon.
• X 1658-298 - has declined from ~20 mCrab to 5 to 10 mCrab (but the latest results are somewhat sparse and noisy).
• EXO 1745-248 - continues to decline and has a srength of ~20 mCrab at week's end.
• Aql X-1 - has remained for about a week at 0.6 Crab.

11 October, 2000 --

Week 244 results (2000 September 29 - October 5)

• Aql X-1 - The current outburst has reached 600 mCrab, the highest levels we have seen for this source.
• GRS 1915+105 is relatively bright (900 mCrab).
• Cyg X-3 is relatively strong (350 mCrab).
• 4U 0115+63 has declined to 70 mCrab.
• EXO 1745-248 decreased to ~100 mCrab.
• Mkn 421 is very low (few mCrab)
• Cen X-3 is also very low (few mCrab).

2 October, 2000 --

Week 243 results (2000 September 22 - 28)

• 4U 0115+63 - down to ~140 mCrab
• LMC X-2 - Has gotten a bit stronger with strength up to ~35 mCrab. This type of increase is unusual for this relatively steady source.
• X 1246-588 - A bit higher than usual (but by no means a record in the ASM era) at ~20 mCrab
• 4U 1705-44 - up to 25 or 30 mCrab
• EXO 1745-248 - decreased to ~100 mCrab
• Aql X-1 - Another outburst has begun in X-rays with flux up to ~50 mCrab and still rising. (The optical precursor of this outburst has been noted by Jain et al. See IAU Circ. No. 7495.)

25 September, 2000 --

• 4U 0115+63 - ~170 mCrab and rather steady in strength
• Cen X-3 - no longer in an X-ray high state at 50 mCrab or less
• 4U 1705-44 - was down to < 15 mCrab and is back up to ~20 mCrab
• EXO 1745-248 - down to ~160 mCrab
• 3A 1942+274 - back up to ~14 mCrab

15 September, 2000 --

• 4U 0115+63 - up to ~150 mCrab
• Her X-1 - appears to be rising to ~20 mCrab at the end of the week; together with the indication of a small increase in flux about 35 days earlier, this may be the end of the long low X-ray intensity interval
• 4U 1705-44 - down to ~40 mCrab
• EXO 1745-248 - down to ~200 mCrab

Note: The accuracy of the S/C attitude solution, which is important for the determination of the ASM results, started to deteriorate beginning on Sept. 6, a day and a half before the end of week 240. Nonetheless, the results for that time interval look reasonable (but should be used with caution). The quality of the attitude data continued to degrade during much of week 241, until the problem was corrected on Sept. 12 or 13 (UT). During much of week 241, the errors in the attitude solution were large enough to severely affect the ASM results.

7 September, 2000 --

• 4U 0115+63 - an outburst is beginning, i.e., with intensity up to 100 mCrab
• X 1417-624 - possibly up to ~13 mCrab (but this could be noise)
• EXO 1745-248 - only 1 measurement this week (at ~100 mCrab)

29 August, 2000 --

• X 1657-415 - flux increased to ~60 mCrab for 1 or 2 days
• X 1730-333 (Rapid Burster) - back to quiescence (<13 mCrab)
• EXO 1745-248 - strong increase to ~370 mCrab
• GRS 1747-312 - noisy data suggests flux of ~40 mCrab
• GRS 1915+105 - mostly not too far from 1 Crab in 90 s averages
• 3A 1942+274 - down to ~10 mCrab
• X 1953+319 - variable with peak intensity of ~40 mCrab
• Cyg X-1 - became a bit more active than in the last few months, with 90 s averages showing activity in the range 0.3 to 0.8 Crab
• Cyg X-3 - increased activity apparent with daily averages as high as 0.4 Crab

15 August, 2000 --

• Her X-1 - up to ~15 mCrab for a few days which could mean the end of this long soft X-ray low state (in 35 days we can look for another peak)
• X 1730-333 (Rapid Burster) - mostly ~13 mCrab
• EXO 1745-248 - declined to ~50 mCrab
• GRS 1747-312 - on the basis of a few good days of data this week, appears to be ~25 mCrab (but many of the other measurements within the past few weeks look very noisy)
• GRS 1915+105 - active in the range 0.3 to 1.6 Crab this week
• 3A 1942+274 - down to ~12 mCrab
• 4U 2206+54 - down from ~13 mCrab to < 7 mCrab

7 August, 2000 --

• XTE J1118+480 - now <10 mCrab
• X 1730-333 (Rapid Burster) - ~15 mCrab
• EXO 1745-248 - went above ~130 mCrab and rapidly down to ~90 mCrab
• GRS 1915+105 - back down to a steady quiet state (in 90 s averages) at ~0.5Crab
• Cyg X-3 - up to ~260 mCrab in daily averages
• 4U 2206+54 - ~13 mCrab

4 August, 2000 --

• X 1730-333 (Rapid Burster) - 25 to 50 mCrab
• EXO 1745-248 - up to 80 mCrab
• SAX J1747.0-2853 - still 15 to 20 mCrab
• GRS 1915+105 - 0.5 to 2.5 Crab in 90 s averages
• 3A 1942+274 - ~25 mCrab
• Cyg X-3 - daily averages up to ~130 mCrab
• SS Cygni - daily averages up to ~25 mCrab

25 July, 2000 --

• X 1730-333 (Rapid Burster) - outburst peaked at ~130 mCrab (daily average) and has now declined to ~40 mCrab at week's end
• EXO 1745-248 - ~50 mCrab (this source is newly activated in the ASM catalog)
• AX J1820.5-1434 - ~20 mCrab
• GRS 1915+105 - very active with 90 s average intensities up to 1.5 Crab
• 3A 1942+274 - nearly 25 mCrab
• Cyg X-1 - very low at ~160 mCrab
• X1957+115 - up to ~50 mCrab

17 July, 2000 --

• Cir X-1 - "baseline" in the last full 16.6 d cycle was lower than ever for the ASM, i.e., in the range 530 to 750 mCrab
• X 1730-333 (Rapid Burster) - appears to be starting another outburst with strength up to 50 mCrab (a peak at quicklook results from week 233 helped here)
• GRS 1915+105 - relatively steady in 90 s averages and at ~500 mCrab
• 3A 1942+274 - up to ~18 mCrab

10 July, 2000 --

• Source in Gl. Cl. NGC 1851 - appears to be relatively strong at 20 to 30 mCrab
• Mkn 421 - ~13 mCrab
• XTE J1118+480 - still about 30 mCrab
• Cen X-3 - has returned from a quiescent interlude to an active phase
• GRS 1915+105 - less active and weaker than last week

6 July, 2000 --

• GRS 1915+105 - highly variable within 0.3 to 1.3 Crab limits

Not much very interesting this week - the number of observations may have been somewhat on the low side. 26 June, 2000 --

• XMkn 421 - is now below ~7 mCrab
• Cir X-1 - downward trend of "baseline" continues to ~0.67 Crab
• X1953+319 - rising to ~20 mCrab
• Cyg X-3 - stable at ~100 mCrab

The sky is quiet (summer vacation?).

19 June, 2000 --

• XTE J1118+480 - rose or at least remained stable in strength (~30 mCrab)
• KS 1731-260 - stable at ~100 mCrab
• 3A 1942+274 - remains at ~10 mCrab
• Cyg X-3 - decreased quite significantly, down to a daily average of ~90 mCrab from 180 to 250 mCrab last week

6 June, 2000 --

• Mkn 421 - about 13 mCrab
• XTE J1118+480 - down to ~28 mCrab
• Cen X-3 - continues in a low intensity state, < 20 mCrab
• XTE J1550-564 - not convincingly detectable (<15 mCrab)
• KS 1731-260 - up to ~100 mCrab
• SAX J1747.0-2853 - ~20 mCrab
• GRS 1915+105 - continues steady at ~0.67 Crab

6 June, 2000 --

• Mkn 421 - ~10 mCrab
• XTE J1118+480 - still around 30 mCrab
• Cen X-3 - X-rays are largely "off" again; <~20 mCrab
• X 1323-619 - increased to 13 to 25 mCrab which is as strong as this source has been in 4 years
• XTE J1550-564 - down to ~10 mCrab
• SAX J1747.0-2853 - down to ~40 mCrab

1 June, 2000 --

• LMC X-3 - flux increased to ~25 mCrab
• Mkn 421 - down to ~15 mCrab
• Cen X-3 - appears to be approaching another low state
• XTE J1550-564 - rapid decline continued to ~20 mCrab
• KS 1731-260 - roughly 30 mCrab
• GRS 1915+105 - relatively steady at ~0.7 Crab

24 May, 2000 --

• Mkn 421 - still strong at > 25 mCrab
• XTE J1118+480 - starting to decline slowly; down to ~30 mCrab
• X1246-588 - roughly 20 mCrab
• XTE J1550-564 - down to ~130 mCrab
• GRS 1915+105 - around 670 mCrab

15 May, 2000 --

• Mkn 421 - daily averages fluctuated between 10 and 40 mCrab
• XTE J1118+480 - down to ~35 mCrab
• sXTE J1550-564 - down to ~260 mCrab

10 May, 2000 --

• Mkn 421 - strong at about 30 mCrab
• XTE J1118+480 - just above ~40 mCrab
• Cen X-3 - is particularly strong; up to ~330 mCrab
• Cir X-1 - "baseline" may be declining slowly
• XTE J1550-564 - declined moderately rapidly to ~540 mCrab
• X 1657-415 - 40 to 60 mCrab

1 May, 2000 --

• XTE J1118+480 - still ~40 mCrab
• XTE J1550-564 - increased sharply to about 1 Crab
• X1608-522 - up to ~90 mCrab at week's end
• SAX J1747.0-2853 - up to ~80 mCrab

28 April, 2000 --

• X0614+091 - up to ~100 mCrab
• XTE J1118+480 - still nearly 40 mCrab
• XTE J1550-564 - up to ~200 mCrab
• X1657-415 - still active; around 30 to 40 mCrab
• KS 1731-260 - up to ~120 mCrab
• SAX J1747.0-2853 - 40 to 60 mCrab
• 3A 1942+274 - up to ~23 mCrab

18 April, 2000 --

• LMC X-3 - is relatively weak, < 10 mCrab
• XTE J1118+480 - remains near 35 mCrab
• XTE J1550-564 - up to ~140 mCrab at week's end
• X1657-415 - active again with intervals up to ~40 mCrab
• X1730-333 (Rapid Burster) - down to < 10 mCrab
• KS 1731-260 - ~50 mCrab
• SAX J1747.0-2853 - roughly 30 mCrab with weak evidence of variability
• M15 (glob. cluster source) - down to ~10 mCrab

11 April, 2000 --

• XTE J1118+480 - ~40 mCrab
• X 1246-588 - oscillating between 0 and 40 mCrab with a ~10 day time-scale
• XTE J1550-564 - another outburst begins, up to ~60 mCrab
• X 1657-415 - some evidence for increased strength of up to ~50 mCrab
• X 1730-333 (Rapid Burster) - still at ~50 mCrab
• SAX J1747.0-2853 - down to ~30 mCrab

3 April, 2000 --

• XTE J1118+480 - ~30 mCrab
• X 1730-333 (Rapid Burster) - appears to be up to ~50 mCrab, but such behavior would be new and different from the earlier outbursts seen with the ASM
• SAX J1747.0-2853 - appears to have decreased to ~25 mCrab
• X 1916-053 - temporarily increased to ~40 mCrab
• GRO J2058+42 - temporarily up to ~13 mCrab
• SAX J21035+4545 - ~13 mCrab

28 March, 2000 --

• Cen X-3 - ~220 mCrab
• XTE J1543-568 - ~20 mCrab
• 4U 1705-44 - up to ~350 mCrab
• XTE J1859+226 - no longer detectable (< 7mCrab)
• GRO J2058+42 - up to ~13 mCrab

21 March, 2000 --

• NGC 1851 (glob. cl. source 0512-401) - ~16 mCrab
• Cen X-3 - widely varying from very weak to 150 mCrab
• X 1246-588 - ~25 mCrab
• X 1608-522 - rather weak, < 10 mCrab
• 4U 1705-44 - up to ~260 mCrab
• SAX J1747.0-2853 - ~100 mCrab
• XTE J1859+226 - < 10 mCrab
• 3A 1942+274 - < 10 mCrab
• M15 (glob. cl. source 2127+119) - ~40 mCrab

14 March, 2000 --

• Cen X-3 - as strong as ~280 mCrab
• X 1246-588 - back up to ~25 mCrab
• XTE J1543-568 - this pulsar (found relatively recently) is at 10 mCrab
• XTE J1859+226 - < 10 mCrab at the end of the week
• GRS 1915+105 - steady at ~1/3 Crab

8 March, 2000 --

• Cen X-3 - relatively weak again, < 80 mCrab
• X1417-624 - < 10 mCrab
• X1608-522 - creeping up to ~70 mCrab
• 4U 1705-44 - up to ~150 mCrab
• KS 1731-260 - ~40 mCrab
• XTE J1859+226 - ~15 mCrab

1 March, 2000 --

• RXJ08124-312 - < 10 mCrab
• Mkn 421 - < 13 mCrab
• Cen X-3 - up to ~200 mCrab in 90 s averages
• X1246-588 - ~25 mCrab
• X1417-624 - ~7 mCrab
• 4U 1705-44 - ~30 mCrab
• XTE J1859+226 - 10 to 15 mCrab
• Cyg X-3 - not quite as active as last week, with 90 s averages up to ~330 mCrab

22 February, 2000 --

• RXJ08124-312 - declined, midweek, to < 10 mCrab
• Mkn 421 - looks to be varying on time scales of days from < 5 to ~20 mCrab (but some or most of this variability is measurement noise)
• 3A 1942+274 - ~18 mCrab
• Cyg X-1 - flaring up above 1 Crab in 90 s averages
• Cyg X-3 - slightly more active than last week, w/ daily averages ~1/3 Crab

18 February, 2000 --

• RXJ08124-312 - up to ~13 mCrab
• Mkn 421 - >~15 mCrab
• XTE J1859+226 - down to ~20 mCrab
• GRS 1915+105 - a bit active, with intensities (90 s averages) of 0.4 to 1.2 Crab
• Cyg X-3 - more active with 90 s averages of 130 to 400 mCrab

8 February, 2000 --

• Cen X-3 - is reappearing with intensities this week as high as ~150 mCrab
• XTE J1859+226 - down to ~25 mCrab
• Cyg X-3 - is somewhat more active with daily averages above 200 mCrab

2 February, 2000 --

• Mkn 421 - last 4 days show intensity of ~7 mCrab, down from earlier in the week and the last week or two
• Cen X-3 - there was no significant intensity increase this week
• X 1145-616 - consistently 7 - 13 mCrab
• X 1246-588 - varying with intensity up to ~25 mCrab
• XTE J1859+226 - down to ~40 mCrab

27 January, 2000 --

• LMC X-3 - strength continues to decline slowly and is now ~10 mCrab
• Mkn 421 - up to ~10 mCrab
• Cen X-3 - There is a hint that this may be waking up after being "dormant" for more than 3 months.
• X1145-616 - around 10 mCrab
• X1417-624 - data are less noisy than last week and still suggest ~20 mCrab strength
• XTE J1859+226 - steady at ~60 mCrab
• 3A 1942+274 - back up to ~25 mCrab

19 January, 2000 --

• LMC X-3 - has declined from ~25 to ~12 mCrab over the last few months
• X 1417-624 - data are noisy but suggest ~20 mCrab strength
• X 1608-522 - data now suggest ~30 mCrab intensity
• XTE J1859+226 - declined slightly to ~80 mCrab
• Cyg X-3 - is becoming more active with 1 dwell intensities sometimes exceeding 250 mCrab

17 January, 2000 --

• X 0614+091 - is back to a stronger (50-75 mCrab) and more variable mode
• X 1608-522 - went down to ~100 mCrab (on the basis of relatively few observations)
• XTE J1859+226 - showed a very slight decline in strength, still ~120 mCrab
• GRS 1915+105 - is back in the low steady mode at ~0.5 Crab
• Cyg X-2 - reached a relatively high flux at ~1.1 Crab
• E 2259+586 - showed an unusual outburst at ~40 mCrab

4 January, 2000 --

• X 0614+091 - has had a strength that has remained rather constant (~40 mCrab) for about 3 weeks, in contrast to the usual up and down pattern with a 1 week time scale.
• X 1608-522 - Strength is increasing, and is up to 200 mCrab. This is likely to be another strong outburst.
• XTE J1859+226 - remains steady at ~130 mCrab
• GRS 1915+105 - flaring activity continues with decreasing strength
• SAX J21035+4545 - Varying in 5 - 15 mCrab range
• PKS 2155-304 - shows a strength of up to 13 mCrab much, but not all of the week. (It is unclear if this is a reliable result.)

Happy New Year, everyone!

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