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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

19551 results found.

  1. LIGO/Virgo S200302c: No notable candidates in GOTO imaging
  2. GRB 200306C: Swift detection of a burst with an optical counterpart
  3. LIGO/Virgo S200302c : No significant candidates in FRAM - TAROT - GRANDMA observations.
  4. LIGO/Virgo S200225q: No notable candidates in GOTO imaging
  5. GRB 200303A: Swift-BAT refined analysis
  6. GRB 200303A: Swift/UVOT Upper Limits
  7. GRB 200303A: GOTO observations upper limit
  8. GRB 200303A: Optical limit from CAHA
  9. GRB 200303A: Enhanced Swift-XRT position
  10. GRB 200303A: Swift detection of a burst
  11. LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
  12. LIGO/Virgo S200302c: no counterpart candidates in the Swift/BAT observations
  13. LIGO/Virgo S200302c: No counterpart candidates in HAWC observations
  14. LIGO/Virgo S200302c: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  15. LIGO/Virgo S200302c : no neutrino counterpart candidate in ANTARES search
  16. GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate
  17. LIGO/Virgo S200225q : No significant candidates in TAROT - FRAM - GRANDMA observations.
  18. GRB 200228B: RATIR Optical Observations
  19. GRB 200228B: Liverpool Telescope imaging
  20. GRB 200228B: Swift/UVOT Upper Limits
  21. GRB 200228B: RATIR Optical Observations
  22. GRB 200227A: RATIR Optical Observations
  23. GRB 200227A: Mondy optical upper limit
  24. GRB 200228B: Enhanced Swift-XRT position
  25. Fermi-LAT Gamma-ray Observations of IceCube-200227A
  26. GRB 200228B: Swift detection of a burst
  27. GRB 200227A: Swift-XRT refined Analysis
  28. GRB 200227A: Swift-BAT refined analysis
  29. GRB 200227A: Swift/UVOT Upper Limits
  30. GRB 200227A: Enhanced Swift-XRT position
  31. HAWC-200216A: No Neutrino Counterpart in ANTARES Search
  32. GRB 200224A: Mondy optical upper limit
  33. LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations
  34. IceCube-200227A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  35. GRB 200227A: Swift detection of a burst
  36. LIGO/Virgo S200224car: GRAWITA VST-ESO PARANAL observations.
  37. Konus-Wind observation of GRB 200219A
  38. GRB 200224A: Calar Alto 2.2m optical afterglow detection
  39. GRB 200219A: Chandra rapid ToO upper limit
  40. LIGO/Virgo S200225q: no counterpart candidates in the Swift/BAT observations
  41. LIGO/Virgo S200224ca: no counterpart candidates in the Swift/BAT observations
  42. GRB 200224B: DDOTI/OAN optical observations report
  43. LIGO/Virgo S200224ca: No Counterparts in DDOTI/OAN Optical Observations
  44. LIGO/Virgo S200224ca: GRAWITA-Campo Imperatore observations.
  45. LIGO/Virgo S200225q: No counterpart candidates in Fermi-LAT observations
  46. LIGO/Virgo S200224ca: Subaru/Hyper Suprime-Cam follow-up observations
  47. LIGO/Virgo S200225q: No counterpart candidates in HAWC observations
  48. LIGO/Virgo S200225q : no neutrino counterpart candidate in ANTARES search
  49. LIGO/Virgo S200224ca: No counterpart candidates in Fermi-LAT observations
  50. LIGO/Virgo S200225q: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  51. LIGO/Virgo S200225q: Coverage and upper limits from MAXI/GSC observations
  52. LIGO/Virgo S200224ca: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  53. GRB 200224A: RATIR Optical Observations and Confirmation of the Afterglow
  54. GRB 200224A: Swift/UVOT Detection
  55. GRB 200224A: Swift-XRT refined Analysis
  56. GRB 200224C: Fermi GBM Final Real-time Localization
  57. GRB 200224A: Tautenburg observations
  58. GRB 200224A: BOOTES-1 and 1.5m OSN optical observations
  59. Fermi trigger No 604213554: Global MASTER-Net observations report
  60. GRB 200224B: Fermi GBM Final Real-time Localization
  61. GRB 200224A: Swift detection of a burst
  62. Swift GRB200224.14: Global MASTER-Net observations report
  63. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC-F30 observations
  64. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC observations
  65. LIGO/Virgo S200219ac : No significant candidates in TAROT - FRAM - GRANDMA observations.
  66. GRB 200219C: OAJ afterglow confirmation
  67. GRB 200219A: UVOT Upper Limits
  68. GRB 200219C: Mondy and TSHAO optical observations
  69. GRB 200219C: Nanshan/NEXT optical upper limit and possible host galaxy from PanSTARRS
  70. GRB 200219C: Swift-XRT afterglow detection
  71. GRB 200219C: DDOTI Observations
  72. GRB 200219C: Tiled Swift observations
  73. LIGO/Virgo S200219ac: no counterpart candidates in the Swift/BAT observations
  74. LIGO/Virgo S200219ac: No counterpart candidates in Fermi-LAT observations
  75. GRB 200219A: Swift-XRT refined Analysis correction
  76. GRB 200219A: Swift-XRT refined Analysis
  77. GRB 200219A: Enhanced Swift-XRT position
  78. LIGO/Virgo S200219ac: upper limits from AGILE/MCAL observations
  79. LIGO/Virgo S200219ac : no neutrino counterpart candidate in ANTARES search
  80. LIGO/Virgo S200219ac: No counterpart candidates in HAWC observations
  81. LIGO/Virgo S200219ac: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  82. GRB 200216B: second epoch optical upper limit at Mondy observatory
  83. GRB 200219A: Swift detection of a short burst
  84. GRB 200216B: Mondy and AbAO optical upper limits
  85. LIGO/Virgo (S200213t/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  86. GRB 200216B: Swift-XRT refined Analysis
  87. LIGO/Virgo S200213t : No significant candidates in FRAM - OAJ - TAROT - GRANDMA observations
  88. GRB 200216B: z-band limit from NOT
  89. GRB 200216B: Swift/UVOT Upper Limits
  90. GRB 200216B: Enhanced Swift-XRT position
  91. GRB 200215A: RATIR Optical Observations
  92. GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
  93. GRB 200216B: GMG upper limit
  94. GRB 200216B: Swift detection of a burst
  95. GRB 200215A: UKIRT H-band observations
  96. GRB 200215A: Swift/UVOT Upper Limits
  97. GRB 200215A: Enhanced Swift-XRT position
  98. GRB 200215A: Optical observations form Calar Alto 2.2m
  99. GRB 200215A: Liverpool Telescope upper limits
  100. LIGO/Virgo S200213t: Pre-discovery detections of MASTER OT J044008.76-651302.3

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