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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"

5822 results found.

  1. GRB 241112B: AbAO optical upper limit
  2. Fermi GRB 241112A: Global MASTER-Net observations report
  3. GRB 241112B: Swift-XRT afterglow detection
  4. GRB 241112B: SVOM/VT afterglow detection
  5. EP241107a: EP-FXT follow-up observations
  6. GRB 241025C: VZLUSAT-2 detection
  7. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  8. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  10. Fermi trigger No 752878030: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  12. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  13. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  14. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  17. GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
  18. GRB 240511A: LCO upper limits
  19. Fermi GRB 241105A: Global MASTER-Net observations report
  20. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  21. EP241103a: Global MASTER-Net observations report
  22. EP241101a: Global MASTER-Net observations report
  23. Fermi trigger No 752083996: Global MASTER-Net observations report
  24. GRB 241029A: LCO optical detection
  25. Fermi trigger No 752006065: Global MASTER-Net observations report
  26. EP241021a: Swift-UVOT detection
  27. EP241021a: Optical rebrightening observations with Mephisto
  28. GRB 241030A : MITSuME Akeno optical afterglow detection
  29. GRB 241029A: GOTO optical afterglow detection
  30. GRB 241029A: MASTER early optical counterpart detection
  31. GRB 241029A: TRT optical afterglow candidate detection
  32. EP 241026b: LBT optical observations
  33. GRB 241026A: SAO RAS observations of possible optical afterglow
  34. Fermi trigger No 751554401: Global MASTER-Net observations report
  35. Fermi trigger No 751449953: Global MASTER-Net observations report
  36. EP241021a: TRT optical observations
  37. GRB 241009A: LCO optical upper limits
  38. GRB 241006A: ATCA Radio Upper Limits
  39. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  42. Fermi GRB 241008A: Global MASTER-Net observations report
  43. IceCube-241006A: No candidates from the Zwicky Transient Facility
  44. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  45. GRB 240910A: LBT optical observations
  46. Fermi trigger No 749721670: Global MASTER-Net observations report
  47. GRB 240930B / EP 240930a: SVOM/GRM observation
  48. Fermi trigger No 749735279: Global MASTER-Net observations report
  49. Fermi trigger No 749630753: Global MASTER-Net observations report
  50. Fermi trigger No 749693019: Global MASTER-Net observations report
  51. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  52. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  53. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  54. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  55. GRB 241002B: GOTO optical counterpart candidate
  56. GRB 240930B: GRBAlpha detection
  57. GRB 240929A: GRBAlpha detection
  58. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  59. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  60. EP240930a: GOTO optical upper limits
  61. GRB 240929A: SVOM/GRM observation
  62. EP EP240930a: Global MASTER-Net observations report
  63. EP240930a: EP-WXT detection of a fast X-ray transient
  64. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  65. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  66. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  67. AMON NuEM 240926A: Swift XRT Follow-up
  68. GRB 240929A : Leavitt Observatory optical upper limit
  69. Fermi GRB 240930B: Global MASTER-Net observations report
  70. GRB 240825A: LBT optical observations
  71. GRB 240928A: SVOM/GRM observation
  72. Fermi GRB 240930A: Global MASTER-Net observations report
  73. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  74. Fermi trigger No 749339671: Global MASTER-Net observations report
  75. Fermi GRB 240929A: Global MASTER-Net observations report
  76. Integral GRB240929.83: Global MASTER-Net observations report
  77. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  78. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  79. GRB 240926A: SVOM/GRM observation
  80. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  81. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240926A
  82. EP240919a / GRB 240919A: SVOM/VT upper limit
  83. EP240918b and EP240918c: EP-FXT follow-up observations
  84. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  85. GRB 240905B: VZLUSAT-2 detection
  86. EP trigger ID 01709059262: correction to the observation start time and source localization
  87. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  88. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo S240919bn: GOTO optical upper limits
  91. GRB 240918B: AstroSat CZTI detection
  92. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  94. EP240919a: EP-FXT follow-up observation update
  95. EP240913A/GRB 240913C: AbAO optical upper limit
  96. EP240919a / GRB 240919A: Mondy optical upper limit
  97. EP240913a/GRB 240913C: 1.6m Mephisto observations
  98. EP240918a: SVOM/VT upper limit
  99. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  100. GRB 240919A / EP240919a: SVOM/GRM observation

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