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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 231215A: NOT optical observations
  2. GRB 231214A: Swift/UVOT Upper Limits
  3. GRB 231215A: Redshift from OSIRIS+ / GTC
  4. GRB 231205B: VZLUSAT-2 detection
  5. GRB 231204A: VZLUSAT-2 detection
  6. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  7. GRB 231215A: Fermi GBM observation
  8. GRB 231215A: CALET Gamma-Ray Burst Monitor detection
  9. GRB 231215A : OHP/T193 optical afterglow detection
  10. GRB 231215A: Swift/UVOT Detection
  11. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  12. GRB 231215A: Swift-XRT refined Analysis
  13. GRB 231215A: BOOTES-4/MET optical detection
  14. GRB 231215A: AKO Optical Upper Limit
  15. GRB 231215A: AGILE detection
  16. GRB 231214A: Fermi GBM observation
  17. Konus-Wind detection of GRB 231210B
  18. ATCA observations of GRB 231210B
  19. GRB 231215A: Enhanced Swift-XRT position
  20. Fermi trigger No 724326442: Global MASTER-Net observations report
  21. GRB 231214A: REM optical/NIR upper limits
  22. GRB 231215A: GROWTH-India optical follow-up
  23. GRB 231215A : Nanshan/HMT optical observations
  24. GRB 231215A: AstroSat CZTI detection
  25. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  26. GRB 231214A: Swift-XRT refined Analysis
  27. GRB 231215A: Mondy optical bright afterglow detection
  28. GRB 231214A: AstroSat CZTI detection
  29. GRB 231215C: MASTER OT detection
  30. Swift GRB231215.41: Global MASTER-Net observations report
  31. GRB 231215A: Swift-XRT observations
  32. GRB 231215B: Fermi GBM Final Real-time Localization
  33. GRB 231215A: Swift detection of a burst
  34. GRB 231214A: Fermi-LAT detection
  35. GRB 231214A: Enhanced Swift-XRT position
  36. GRB 231214B: Swift/BAT-GUANO detection of a burst
  37. GRB231214A: BOOTES-6/DPRT optical upper limit
  38. Fermi trigger No 724278269: Global MASTER-Net observations report
  39. Fermi trigger No 724233240: Global MASTER-Net observations report
  40. Swift GRB231214.85: Global MASTER-Net observations report
  41. GRB 231214A: Swift detection of a burst
  42. GRB 231214A: Fermi GBM Final Real-time Localization
  43. GRB 231210B: REM optical/NIR upper limits
  44. IceCube-231211A: Upper limits from a search for additional neutrino events in IceCube
  45. LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
  46. LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
  47. Fermi-LAT detection of increased gamma-ray activity of blazar PKS 2047+098, located inside the IceCube-231211A error region
  48. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  49. LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
  50. LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO
  51. GRB 231212A: GECAM-C detection of a likely short burst
  52. Fermi trigger No 724035412: Global MASTER-Net observations report
  53. GRB 231210B: MeerLICHT afterglow observations
  54. GRB 231210B: Swift-BAT refined analysis
  55. IceCube Alert 231211.03: Global MASTER-Net observations report
  56. IceCube-231202A: No candidates from the Zwicky Transient Facility
  57. GRB 231210B: Swift-XRT refined Analysis
  58. GRB 231210B: Enhanced Swift-XRT position
  59. GRB 231210B: VLT/X-shooter redshift
  60. GRB 231210B: detection of the optical counterpart with the LCOGT 40cm telescope at Sutherland Observatory
  61. Fermi trigger No 723906955: Global MASTER-Net observations report
  62. GRB 231210B: Swift detection of a burst with optical counterpart
  63. Swift GRB231210.90: Global MASTER-Net OT detection
  64. Swift GRB231210.90: Global MASTER-Net observations report
  65. IPN triangulation of GRB 231129C
  66. GRB 231210A: Fermi GBM Final Real-time Localization
  67. GRB 231208A: GRBAlpha detection
  68. GRB231205B: Swift/UVOT Upper Limits
  69. GRB 231208A: Glowbug gamma-ray detection
  70. GRB 231208A: AstroSat CZTI detection of a faint burst
  71. LIGO/Virgo/KAGRA S231206ca: Updated Sky localization
  72. IPN triangulation of GRB 231205A
  73. GRB 231205B: Swift-BAT refined analysis
  74. GRB 231205B: 1.3m DFOT Optical upper limit
  75. LIGO/Virgo/KAGRA S231206cc: Updated Sky localization and Source Classification
  76. GRB 231206A: joint location of multiple instruments by ETJASMIN
  77. GRB 231205B: optical upper limit in TSHAOand AbAO
  78. LIGO/Virgo/KAGRA S231206cc: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S231206ca: Identification of a GW compact binary merger candidate
  80. GRB231115A: TURBO Pre-Burst Optical Upper Limits
  81. GRB 231205B: AGILE detection
  82. Fermi trigger No 723581802: Global MASTER-Net observations report
  83. GRB 231206B: Fermi GBM Final Real-time Localization
  84. GRB 231205B: Ondrejov D50 optical upper limit
  85. GRB 231205B: Swift-XRT refined Analysis
  86. Fermi-LAT gamma-ray observations of IceCube-231202A
  87. GRB 231205B: REM optical/NIR upper limits
  88. GRB 231129C: ASIM MXGS observation and localization
  89. GRB 231205B: NUTTelA-TAO / BSTI Early Optical Limits
  90. GRB 231205B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  91. GRB 231206A: GECAM-B detection of a short burst (correction)
  92. GRB 231205B : MITSuME Akeno optical upper limits
  93. GRB 231206A: GECAM-B detection of a short burst
  94. GRB 231205B: Zadko observatory - Gingin optical observations
  95. GRB 231205B: Gaoyazi/GOT optical upper limit
  96. GRB 231205B: Nanshan/HMT optical upper limit
  97. GRB 231205B: GECAM-B detection of a long burst
  98. GRB 231205B: LCOGT Optical Upper Limits
  99. GRB 231205A: DDOTI Upper Limits on the Afterglow
  100. LIGO/Virgo/KAGRA S231205c: One counterpart neutrino candidate event from an IceCube neutrino search

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