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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. IPN triangulation of GRB 241107A (short/hard)
  2. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  3. GRB 241025C: VZLUSAT-2 detection
  4. GRB 241025A: VZLUSAT-2 detection
  5. GRB 241018A: cubesat Avion detection
  6. Fermi trigger No 752990530: Global MASTER-Net observations report
  7. GRB 241111A: Fermi GBM Final Real-time Localization
  8. GRB 241030B: TESS detection of optical counterpart
  9. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  10. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  11. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  12. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  13. Fermi trigger No 752878030: Global MASTER-Net observations report
  14. Integral GRB241109.89: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  16. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  17. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  18. INTEGRAL detection of a burst from 1E 1841-045
  19. EP241107a: AbAO optical upper limit
  20. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  21. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  22. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  23. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  25. EP241109a: confirmation of a stellar flare by BOOTES-7
  26. EP241109a: EP on-board trigger and autonomous follow-up observation
  27. GRB 241108A: Swift-XRT observations
  28. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  29. EP241107A: MASTER optical observations of xray transient
  30. EP241107a: KAIT optical observations
  31. GRB 241108A: Swift ToO observations
  32. GRB 241030A: TESS observations
  33. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  34. GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
  35. EP241107a: Kinder optical follow-up observations
  36. GRB 241025A: radio detection with the VLA
  37. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  38. EP241107a: AKO Optical Afterglow Follow-Up Observations
  39. EP241107a: GSP detects optical counterpart
  40. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  41. GRB 241107A: SVOM/GRM detection of a short burst
  42. GRB 241105A: EP-FXT follow-up observations
  43. GRB 241105A: SVOM/GRM observation
  44. EP241107a: OHP/T193 photometric and spectroscopic observations
  45. GRB 241105a: PRIME near-infrared upper limits
  46. EP241107a: FTW Optical and NIR observations of the optical counterpart
  47. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  48. EP241107a: GIT optical observations
  49. EP241107a: Global MASTER-Net observations report
  50. EP241107a: SVOM/C-GFT optical observations
  51. EP241107a: AKO Optical Afterglow Detection
  52. GRB 241025A: LBT optical observations
  53. GRB241105A: Gemini-South Optical Afterglow Detection
  54. EP241107a: EP on-board trigger and autonomous follow-up observation
  55. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  56. GRB 241105A: Swift/UVOT Detection
  57. EP241101a: CrAO ZTSH optical observations
  58. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  59. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  60. GRB 241105A: BOOTES-7 optical detection
  61. GRB 241030A: Mondy optical observations
  62. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  63. Konus-Wind detection of GRB 241105A (short with extended emission)
  64. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  65. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  66. Konus-Wind detection of GRB 241021A
  67. GRB 241105A: SVOM/VT optical afterglow observations
  68. GRB 241105A: Swift-XRT afterglow detection
  69. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  70. GRB 241104A: Swift-XRT observations
  71. GRB 240511A: LCO upper limits
  72. GRB 241104A: Fermi GBM Observation
  73. GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
  74. GRB 241105A: Swift ToO observations
  75. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  76. GRB 241104A: Swift ToO observations
  77. GRB 241104A: NOT optical non-detection
  78. GRB 241105A: GOTO tentative optical counterpart candidate
  79. Fermi GRB 241105A: Global MASTER-Net observations report
  80. GRB 241104A: SVOM/VT optical candidate
  81. GRB 241105A: Fermi GBM Final Real-time Localization
  82. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  83. GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
  84. GRB 241104A: SVOM/GRM observation
  85. EP241104a: EP detection of GRB 241104A X-ray emission
  86. GRB 241010A: host galaxy redshift z = 0.977
  87. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  88. GRB 241104A : Detection and localization by SVOM/ECLAIRs
  89. GRB 240821A: further radio observations with the VLA
  90. Fermi GRB 241104A: Global MASTER-Net observations report
  91. GRB 241104A: Fermi GBM Final Real-time Localization
  92. GRB 241030A: GRBAlpha detection
  93. EP241101a: EP-FXT observations update
  94. EP241103a: GIT optical upper limit
  95. EP241021a: OHP/T193 further optical observations
  96. LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
  97. Fermi trigger No 752365806: Global MASTER-Net observations report
  98. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  99. LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
  100. EP241103a: GOTO optical upper limit

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