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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: GMG Optical Upper Limit
  2. GRB 241113A: Enhanced Swift-XRT position
  3. GRB241113A: LCOGT (40-cm) optical counterpart detection
  4. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  5. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  6. GRB 241113A: Swift detection of a burst with an optical counterpart
  7. Swift GRB241113.33: Global MASTER-Net observations report
  8. SVOM/GRM detection of a short burst from SGR 1E1841-045
  9. Fermi trigger No 753166198: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  11. GRB 241105A: ATCA Radio Upper Limits
  12. GRB 241112B: AbAO optical upper limit
  13. GRB 241107A: GROWTH-India telescope optical upper limit
  14. IceCube Alert 241113.02: Global MASTER-Net observations report
  15. Fermi GRB 241112A: Global MASTER-Net observations report
  16. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  17. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  18. GRB 241112B: Swift-XRT afterglow detection
  19. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  20. GRB 241112B: SVOM/GRM observation
  21. GRB 241112B: SVOM/VT afterglow detection
  22. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  23. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  24. GRB 241112B: Mephisto optical upper limits
  25. GRB 241112B: GOTO optical upper limits
  26. GRB 241112B: Swift ToO observations
  27. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  28. GRB 241107A: INTEGRAL IBIS localization
  29. EP241107a: EP-FXT follow-up observations
  30. GRB 241112A: Fermi GBM Final Real-time Localization
  31. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  32. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  33. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  34. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  35. IPN triangulation of GRB 241107A (short/hard)
  36. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  37. GRB 241025C: VZLUSAT-2 detection
  38. GRB 241025A: VZLUSAT-2 detection
  39. GRB 241018A: cubesat Avion detection
  40. Fermi trigger No 752990530: Global MASTER-Net observations report
  41. GRB 241111A: Fermi GBM Final Real-time Localization
  42. GRB 241030B: TESS detection of optical counterpart
  43. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  44. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  45. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  47. Fermi trigger No 752878030: Global MASTER-Net observations report
  48. Integral GRB241109.89: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  50. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  51. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  52. INTEGRAL detection of a burst from 1E 1841-045
  53. EP241107a: AbAO optical upper limit
  54. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  55. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  56. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  57. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  58. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  59. EP241109a: confirmation of a stellar flare by BOOTES-7
  60. EP241109a: EP on-board trigger and autonomous follow-up observation
  61. GRB 241108A: Swift-XRT observations
  62. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  63. EP241107A: MASTER optical observations of xray transient
  64. EP241107a: KAIT optical observations
  65. GRB 241108A: Swift ToO observations
  66. GRB 241030A: TESS observations
  67. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  68. GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
  69. EP241107a: Kinder optical follow-up observations
  70. GRB 241025A: radio detection with the VLA
  71. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  72. EP241107a: AKO Optical Afterglow Follow-Up Observations
  73. EP241107a: GSP detects optical counterpart
  74. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  75. GRB 241107A: SVOM/GRM detection of a short burst
  76. GRB 241105A: EP-FXT follow-up observations
  77. GRB 241105A: SVOM/GRM observation
  78. EP241107a: OHP/T193 photometric and spectroscopic observations
  79. GRB 241105a: PRIME near-infrared upper limits
  80. EP241107a: FTW Optical and NIR observations of the optical counterpart
  81. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  82. EP241107a: GIT optical observations
  83. EP241107a: Global MASTER-Net observations report
  84. EP241107a: SVOM/C-GFT optical observations
  85. EP241107a: AKO Optical Afterglow Detection
  86. GRB 241025A: LBT optical observations
  87. GRB241105A: Gemini-South Optical Afterglow Detection
  88. EP241107a: EP on-board trigger and autonomous follow-up observation
  89. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  90. GRB 241105A: Swift/UVOT Detection
  91. EP241101a: CrAO ZTSH optical observations
  92. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  93. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  94. GRB 241105A: BOOTES-7 optical detection
  95. GRB 241030A: Mondy optical observations
  96. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  97. Konus-Wind detection of GRB 241105A (short with extended emission)
  98. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  99. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  100. Konus-Wind detection of GRB 241021A

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