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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. SVOM/GRM detection of a short burst from SGR 1E1841-045
  2. Fermi trigger No 753166198: Global MASTER-Net observations report
  3. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  4. GRB 241105A: ATCA Radio Upper Limits
  5. GRB 241112B: AbAO optical upper limit
  6. GRB 241107A: GROWTH-India telescope optical upper limit
  7. IceCube Alert 241113.02: Global MASTER-Net observations report
  8. Fermi GRB 241112A: Global MASTER-Net observations report
  9. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  10. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  11. GRB 241112B: Swift-XRT afterglow detection
  12. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  13. GRB 241112B: SVOM/GRM observation
  14. GRB 241112B: SVOM/VT afterglow detection
  15. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  16. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  17. GRB 241112B: Mephisto optical upper limits
  18. GRB 241112B: GOTO optical upper limits
  19. GRB 241112B: Swift ToO observations
  20. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  21. GRB 241107A: INTEGRAL IBIS localization
  22. EP241107a: EP-FXT follow-up observations
  23. GRB 241112A: Fermi GBM Final Real-time Localization
  24. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  25. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  26. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  27. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  28. IPN triangulation of GRB 241107A (short/hard)
  29. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  30. GRB 241025C: VZLUSAT-2 detection
  31. GRB 241025A: VZLUSAT-2 detection
  32. GRB 241018A: cubesat Avion detection
  33. Fermi trigger No 752990530: Global MASTER-Net observations report
  34. GRB 241111A: Fermi GBM Final Real-time Localization
  35. GRB 241030B: TESS detection of optical counterpart
  36. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  37. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  38. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  40. Fermi trigger No 752878030: Global MASTER-Net observations report
  41. Integral GRB241109.89: Global MASTER-Net observations report
  42. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  43. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  44. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  45. INTEGRAL detection of a burst from 1E 1841-045
  46. EP241107a: AbAO optical upper limit
  47. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  48. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  49. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  50. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  52. EP241109a: confirmation of a stellar flare by BOOTES-7
  53. EP241109a: EP on-board trigger and autonomous follow-up observation
  54. GRB 241108A: Swift-XRT observations
  55. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  56. EP241107A: MASTER optical observations of xray transient
  57. EP241107a: KAIT optical observations
  58. GRB 241108A: Swift ToO observations
  59. GRB 241030A: TESS observations
  60. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  61. GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
  62. EP241107a: Kinder optical follow-up observations
  63. GRB 241025A: radio detection with the VLA
  64. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  65. EP241107a: AKO Optical Afterglow Follow-Up Observations
  66. EP241107a: GSP detects optical counterpart
  67. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  68. GRB 241107A: SVOM/GRM detection of a short burst
  69. GRB 241105A: EP-FXT follow-up observations
  70. GRB 241105A: SVOM/GRM observation
  71. EP241107a: OHP/T193 photometric and spectroscopic observations
  72. GRB 241105a: PRIME near-infrared upper limits
  73. EP241107a: FTW Optical and NIR observations of the optical counterpart
  74. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  75. EP241107a: GIT optical observations
  76. EP241107a: Global MASTER-Net observations report
  77. EP241107a: SVOM/C-GFT optical observations
  78. EP241107a: AKO Optical Afterglow Detection
  79. GRB 241025A: LBT optical observations
  80. GRB241105A: Gemini-South Optical Afterglow Detection
  81. EP241107a: EP on-board trigger and autonomous follow-up observation
  82. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  83. GRB 241105A: Swift/UVOT Detection
  84. EP241101a: CrAO ZTSH optical observations
  85. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  86. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  87. GRB 241105A: BOOTES-7 optical detection
  88. GRB 241030A: Mondy optical observations
  89. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  90. Konus-Wind detection of GRB 241105A (short with extended emission)
  91. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  92. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  93. Konus-Wind detection of GRB 241021A
  94. GRB 241105A: SVOM/VT optical afterglow observations
  95. GRB 241105A: Swift-XRT afterglow detection
  96. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  97. GRB 241104A: Swift-XRT observations
  98. GRB 240511A: LCO upper limits
  99. GRB 241104A: Fermi GBM Observation
  100. GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source

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