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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.

Lucene Examples (click to copy):

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

24573 results found.

  1. GRB 250328A: AbAO AS-32 Optical Observations
  2. GRB 250219A: NOT candidate host galaxy detection
  3. GRB 250331D: Swift-XRT observations
  4. GRB 250331C: Swift-XRT refined Analysis
  5. GRB 250331B: Swift-XRT refined Analysis
  6. GRB 250331B: Swift-XRT refined Analysis
  7. GRB 250322B possible detection by the AstroSat Satellite
  8. GRB 250330B: SVOM/GRM observation of a short burst
  9. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  10. GRB 250330B: EIRSAT-1 GMOD Detection
  11. GRB 250327A Swift-BAT refined analysis
  12. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  13. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  14. Swift GRB 250331C: Global MASTER-Net observations report
  15. Swift GRB 250331B: Global MASTER-Net observations report
  16. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  17. GRB 250331C: Enhanced Swift-XRT position
  18. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  19. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  20. GRB 250331B: Enhanced Swift-XRT position
  21. GRB 250320C : SVOM detection of a burst through offline search
  22. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  23. GRB 250330A: VLT/FORS2 Afterglow Detection
  24. GRB20250327B: 45th Parallel Observatory upper limit
  25. GRB 250328A: Swift/UVOT Detection
  26. GRB 250328A: Swift-XRT refined Analysis
  27. Fermi-LAT gamma-ray observations of IceCube-250330A
  28. SVOM/sb25033102 is a false trigger
  29. GRB 250330A: Fermi GBM Observation
  30. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  31. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  32. GRB 250331C: Swift detection of a burst
  33. GRB 250331B: Swift detection of a burst
  34. GRB 250331A: MAXI/GSC detection
  35. SVOM/sb25033102: SVOM detection of an X-ray transient
  36. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  37. GRB 250330A: Swift/UVOT Upper Limits
  38. GRB 250330A: Swift-XRT afterglow detection
  39. GRB 250328A: 1.6m Mephisto optical observations
  40. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  41. GRB 250330A: VLT/FORS2 Optical Observations
  42. GRB 250329B: Swift-XRT afterglow detection
  43. GRB 250330A: Swift detection of a burst
  44. GRB 250329B: SVOM/C-GFT optical upper limit
  45. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  46. GRB 250329B: SVOM/VT optical upper limit
  47. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  48. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  49. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  50. GRB250329A: REM optical afterglow detection
  51. GRB 250329A: Swift-XRT afterglow detection
  52. GRB 250328A: SVOM/VT optical observation
  53. GRB 250329A: Fading optical counterpart detection by LCO.
  54. GRB 250328A: SVOM/C-GFT optical upper limit
  55. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  56. GRB 250329A: SVOM/VT optical counterpart confirmation
  57. GRB 250329A: SVOM detection of a burst
  58. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  59. GRB 250327B: J-band observations with WINTER
  60. GRB 250327B: LCO optical counterpart detection
  61. GRB 250328A: SVOM detection of a burst
  62. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  63. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  64. GRB 250327B: CrAO and SAO RAS Optical Observations
  65. GRB 250327b: Liverpool Telescope optical observations
  66. GRB 250322A: GRANDMA/TNOT optical upper limits
  67. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  68. GRB 250327A: SVOM/VT upper limits on the XRT position
  69. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  70. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  71. GRB 250327B: Las Cumbres optical counterpart detection
  72. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  73. GRB 250327B: 1.6m Mephisto optical observations
  74. GRB 250327A: Swift-XRT refined Analysis
  75. GRB 250327B: SVOM/VT optically bright counterpart
  76. GRB 250327B: SAO RAS optical candidate
  77. GRB 250327B: SVOM detection of a burst
  78. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  79. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  80. GRB 250327A: J-band observations with WINTER
  81. GRB 250327A: SVOM/VT optical candidate
  82. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  83. GRB 250327A: DDOTI Optical Observations
  84. GRB 250327A: COLIBRÍ optical upper limit
  85. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  86. IPN triangulation of GRB 250322B
  87. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  88. EP250321a: Mondy AZT-33IK Continued Optical Observations
  89. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  90. GRB 250322A: third epoch of NOT optical observations
  91. GRB 250322A: Swift-BAT refined analysis
  92. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  93. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  94. GRB 250322A: further NOT optical observations
  95. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  96. GRB 250322A: Swift/UVOT Upper Limits
  97. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  98. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  99. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  100. GRB 250321B: Swift-XRT observations

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