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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"

19550 results found.

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

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