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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"
  1. GRB 240819A: Swift afterglow confirmation
  2. GRB 240825A: TNG optical photometry and spectroscopy
  3. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  4. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  5. GRB 240825A: NUTTelA-TAO / BSTI Optical Limits
  6. GRB 240825A: GMG Continued Optical Observation on the Second Night
  7. GRB 240824B: Ondrejov D50 optical limit
  8. GRB 240825A: KAIT optical observations
  9. GRB 240825A: PRIME near-infrared detection
  10. Konus-Wind detection of GRB 240825A (bright/long)
  11. GRB 240825A: Fermi GBM Observation
  12. GRB 240825A : MISTRAL/T193 OHP optical follow-up of the afterglow
  13. GRB 240825A: AKO Optical Follow-Up Observations
  14. GRB 240825A: AstroSat CZTI detection of the long bright burst
  15. SGR 1E 1841-045 / Kes 73: SVOM/GRM observation
  16. GRB 240825A: Swift/UVOT Detection
  17. GRB 240825A: REM detection of the optical/NIR afterglow
  18. GRB 240825A: Swift-XRT refined Analysis
  19. GRB 240825A: VLT/X-shooter redshift
  20. GRB 240825A: SVOM/C-GFT optical observations
  21. GRB 240825A: Montarrenti Observatory optical observations
  22. GRB 240825A: Enhanced Swift-XRT position
  23. GRB 240825A: MASTER optical counterpart observation
  24. GRB 240825A: Fermi-LAT detection
  25. GRB 240825A: LCO optical observations
  26. GRB 240824B: KAIT optical upper limit
  27. SGR 1E 1841-045 / Kes 73 (Trigger 1249878): Osservatorio Atronomico Nastro Verde optical upper limit
  28. GRB 240824B: Fermi GBM Observation
  29. Fermi GRB 240825A: Global MASTER-Net observations report
  30. SGR 1E 1841-045 / Kes 73 (Trigger 1249653) - Osservatorio Astronomico Nastro Verde upper limit
  31. GRB 240824B: NOT optical upper limit
  32. GRB 240825A: GMG Optical Observation
  33. Swift GRB 240825A: Global MASTER-Net observations report
  34. GRB 240825A: 1.6m Mephisto multi-band detection
  35. GRB 240825A: AKO Optical Afterglow Detection
  36. GRB 240825A: Skynet Optical Afterglow observations
  37. GRB 240825A: Nanshan/HMT optical afterglow observations
  38. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  39. GRB 240825A: Fermi GBM Final Real-time Localization
  40. GRB 240824A: Swift-BAT refined analysis
  41. GRB 240824A: SVOM/C-GFT optical upper limit
  42. GRB 240824B: Swift-XRT afterglow detection
  43. GRB 240824A: Swift-XRT observations
  44. LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
  45. GRB 240824B: Swift/BAT arcminute localization of a burst
  46. GRB 240824B: Swift ToO observations
  47. Fermi GRB 240824C: Global MASTER-Net observations report
  48. GRB 240824C: Fermi GBM Final Localization
  49. GRB 240824A: Swift/UVOT Upper Limits
  50. GRB 240821A: Swift/UVOT observations of the XRT sources.
  51. GRB 240824B: MAXI/GSC detection
  52. GRB 240824B: Fermi GBM Final Real-time Localization
  53. GRB 240824A: Retraction of GCN 37255
  54. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  55. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  56. GRB 240824A: KAIT optical upper limit
  57. GRB 240824A: Skynet Optical Afterglow Discovery
  58. GRB 240824A: Swift detection of a burst
  59. Swift GRB240824.04: Global MASTER-Net observations report
  60. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  61. GRB 240821A: Colibri Optical Upper Limit
  62. EP240820a: PRIME J-band Observations
  63. GRB 240821A: Swift-XRT observations
  64. GRB 240822A: AstroSat CZTI detection of a short burst
  65. GRB 240821A: REM optical/NIR upper limits
  66. GRB 240821A: LCO optical observations
  67. GRB 240821A: JinShan optical upper limits
  68. GRB 240809A: Mondy and AbAO Optical Observations
  69. GRB 240821A: SVOM/VT follow-up and optical upper limit
  70. GRB 240821A: GMG Optical Upper Limit
  71. Fermi GRB 240821A: Global MASTER-Net observations report
  72. GECAM-B observation of a short burst from SGR 1E 1841-045 / Kes 73
  73. GRB 240821A: Fermi GBM Observation
  74. Fermi trigger No 745964969: Global MASTER-Net observations report
  75. Fermi trigger No 745925274: Global MASTER-Net observations report
  76. GRB 240821A: Swift ToO observations
  77. Fermi trigger No 746019401: Global MASTER-Net observations report
  78. Fermi-GBM Observations of the reactivation of SGR 1E 1841-045 / Kes 73
  79. Fermi trigger No 745935375: Global MASTER-Net observations report
  80. GRB240821A: EIRSAT-1 GMOD Detection
  81. GRB240821B: First GRB Detected by EIRSAT-1 GMOD
  82. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  83. Fermi GRB 240821B: Global MASTER-Net observations report
  84. EP240801a: Keck/LRIS spectroscopic redshift confirmation
  85. GRB 240821A: SVOM/GRM observation
  86. GRB 240821A: SVOM/GRM observation
  87. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  88. GRB 240821B: Fermi GBM Final Localization
  89. Fermi trigger No 745866488: Global MASTER-Net observations report
  90. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  91. GRB 240821A: BALROG localization (Fermi Trigger 745958167 / GRB 240821775)
  92. GRB 240821A : a likely short GRB detected by SVOM/ECLAIRs
  93. GRB 240821A: Fermi GBM Final Real-time Localization
  94. GRB 240819A: Swift-XRT observations
  95. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  96. GRB 240820B: SVOM/GRM observation
  97. EP240820a: TRT optical upper limit
  98. EP240820a: EP detection of a fast X-ray transient
  99. GRB 240819A: KAIT optical upper limit
  100. EP240816a: PRIME upper limits

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