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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 241112B: LCO optical detection of the SVOM/VT candidate
  2. GRB 241112B: SVOM/GRM observation
  3. GRB 241112B: SVOM/VT afterglow detection
  4. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  5. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  6. GRB 241112B: Mephisto optical upper limits
  7. GRB 241112B: GOTO optical upper limits
  8. GRB 241112B: Swift ToO observations
  9. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  10. GRB 241107A: INTEGRAL IBIS localization
  11. EP241107a: EP-FXT follow-up observations
  12. GRB 241112A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  14. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  15. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  16. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  17. IPN triangulation of GRB 241107A (short/hard)
  18. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  19. GRB 241025C: VZLUSAT-2 detection
  20. GRB 241025A: VZLUSAT-2 detection
  21. GRB 241018A: cubesat Avion detection
  22. Fermi trigger No 752990530: Global MASTER-Net observations report
  23. GRB 241111A: Fermi GBM Final Real-time Localization
  24. GRB 241030B: TESS detection of optical counterpart
  25. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  26. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  27. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  29. Fermi trigger No 752878030: Global MASTER-Net observations report
  30. Integral GRB241109.89: Global MASTER-Net observations report
  31. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  32. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  33. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  34. INTEGRAL detection of a burst from 1E 1841-045
  35. EP241107a: AbAO optical upper limit
  36. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  37. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  38. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  39. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  40. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  41. EP241109a: confirmation of a stellar flare by BOOTES-7
  42. EP241109a: EP on-board trigger and autonomous follow-up observation
  43. GRB 241108A: Swift-XRT observations
  44. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  45. EP241107A: MASTER optical observations of xray transient
  46. EP241107a: KAIT optical observations
  47. GRB 241108A: Swift ToO observations
  48. GRB 241030A: TESS observations
  49. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  50. GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
  51. EP241107a: Kinder optical follow-up observations
  52. GRB 241025A: radio detection with the VLA
  53. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  54. EP241107a: AKO Optical Afterglow Follow-Up Observations
  55. EP241107a: GSP detects optical counterpart
  56. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  57. GRB 241107A: SVOM/GRM detection of a short burst
  58. GRB 241105A: EP-FXT follow-up observations
  59. GRB 241105A: SVOM/GRM observation
  60. EP241107a: OHP/T193 photometric and spectroscopic observations
  61. GRB 241105a: PRIME near-infrared upper limits
  62. EP241107a: FTW Optical and NIR observations of the optical counterpart
  63. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  64. EP241107a: GIT optical observations
  65. EP241107a: Global MASTER-Net observations report
  66. EP241107a: SVOM/C-GFT optical observations
  67. EP241107a: AKO Optical Afterglow Detection
  68. GRB 241025A: LBT optical observations
  69. GRB241105A: Gemini-South Optical Afterglow Detection
  70. EP241107a: EP on-board trigger and autonomous follow-up observation
  71. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  72. GRB 241105A: Swift/UVOT Detection
  73. EP241101a: CrAO ZTSH optical observations
  74. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  75. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  76. GRB 241105A: BOOTES-7 optical detection
  77. GRB 241030A: Mondy optical observations
  78. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  79. Konus-Wind detection of GRB 241105A (short with extended emission)
  80. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  81. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  82. Konus-Wind detection of GRB 241021A
  83. GRB 241105A: SVOM/VT optical afterglow observations
  84. GRB 241105A: Swift-XRT afterglow detection
  85. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  86. GRB 241104A: Swift-XRT observations
  87. GRB 240511A: LCO upper limits
  88. GRB 241104A: Fermi GBM Observation
  89. GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
  90. GRB 241105A: Swift ToO observations
  91. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  92. GRB 241104A: Swift ToO observations
  93. GRB 241104A: NOT optical non-detection
  94. GRB 241105A: GOTO tentative optical counterpart candidate
  95. Fermi GRB 241105A: Global MASTER-Net observations report
  96. GRB 241104A: SVOM/VT optical candidate
  97. GRB 241105A: Fermi GBM Final Real-time Localization
  98. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  99. GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
  100. GRB 241104A: SVOM/GRM observation

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