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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"

45414 results found.

  1. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  2. GRB 260822A: EP/FXT follow-up observations
  3. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  4. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  5. EP260822a: EP-FXT non-detection and upper limit
  6. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  7. GRB 260822A: GOTO optical counterpart detection
  8. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  9. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  10. EP260822a: Einstein Probe detection of a fast X-ray transient
  11. GRB 260822A: LCO optical upper limits
  12. The EP-WXT trigger 01709287395 is likely a flaring star
  13. GRB260822B: Fermi GBM Final Localization
  14. GRB 260822A: GROWTH-India Telescope Upper Limits
  15. GRB 260822A: GOTO optical upper limit
  16. GRB 260822A: SVOM detection of a short burst
  17. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  18. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  19. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 260818B: VLA radio observations
  21. GRB 260818B: SVOM/C-GFT optical upper limit
  22. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  23. IceCube Alert 260821A: Global MASTER-Net observations report
  24. The EP-WXT trigger 01709286204 is likely a flaring star
  25. GRB 260820A: Insight-HXMT/HE detection
  26. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 260818B: SVOM/GRM observation
  28. EP detected a brightening of LMXB 1ES 1735-26.9
  29. GRB260820A: Fermi GBM Final Real-Time Localization
  30. GRB 260818B: Insight-HXMT detection
  31. GRB 260818B: EP-FXT follow-up observation
  32. GRB 260818A: J-band observations with WINTER
  33. GRB 260818B: SVOM/ECLAIRs refined analysis
  34. GRB 260818A: SVOM/ECLAIRs refined analysis
  35. GRB 260818B: NOT optical upper limits
  36. GRB 260810A: SVOM/GRM observation
  37. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  38. GRB260818A: EP-FXT follow-up observation
  39. GRB 260818B: LCO optical upper limits
  40. GRB 260818B: SVOM detection of a short burst
  41. SVOM trigger sb26081806 is not a GRB
  42. EP260806a: SAO RAS multicolor optical observations
  43. GRB 260818A: LCO optical upper limits
  44. EP260812a: AbAO optical upper limit
  45. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  46. GRB 260810A: Insight-HXMT/HE detection
  47. GRB 260818A: SVOM possible detection of a long and faint GRB
  48. EP260806a: SVOM/ECLAIRs detection through targeted search
  49. EP260806a: NUTTELA-TAO optical observations
  50. The EP-WXT trigger 01709281429 is likely a flaring star
  51. EP260812a: AZT-22 optical upper limit
  52. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  53. EP260806a: WFST optical observations
  54. The EP-WXT trigger 01709280562 is likely a flaring star
  55. EP260812b: Optical upper limit with Kinder
  56. The EP-WXT trigger 01709279838 is likely a flaring star
  57. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  58. GRB 260808B: Liverpool Telescope further optical observations
  59. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  60. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  61. GRB 260813A: Fermi GBM Final Real-time Localization
  62. EP260812a: NOT and Liverpool Telescope upper limits:
  63. EP260812b: Liverpool Telescope observations
  64. EP260812b: GOTO detection of the optical counterpart
  65. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  66. EP260812a: SVOM/C-GFT optical upper limit
  67. EP260812b: COLIBRÍ optical observations
  68. EP260812b: SVOM/VT optical observation
  69. GRB 260808A: SVOM/GRM observation
  70. EP260812b: Einstein Probe detection of an X-ray transient
  71. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  72. Fermi GBM Sub-Threshold Detection of GRB 260809A
  73. GRB 260810A: Glowbug gamma-ray detection
  74. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  75. GRB 260810A: AstroSat CZTI detection of a long burst
  76. EP260812a: Einstein Probe detection of an X-ray transient
  77. GRB 260809A: SAO RAS optical observations
  78. GRB 260808B: SAO RAS optical observations
  79. GRB 260808B: SVOM/VT optical re-brightening at day 3
  80. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  81. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 260808A: GECAM-B observation
  83. GRB 260807A: SVOM/ECLAIRs refined analysis
  84. EP260806a: MAO/AZT-22 optical observations
  85. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB260808B: MAO/AZT-22 optical observations
  87. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  88. GRB 260809A: J-band upper limit with WINTER
  89. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  90. GRB 260806A: Glowbug gamma-ray detection
  91. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  92. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  93. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  94. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  95. The EP-WXT trigger 01709278015 is likely a flaring star
  96. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  97. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  98. GRB 260809A: NOT optical observations
  99. GRB260809A: MAO/AZT-22 optical observations
  100. GRB260809A: OHP/T193 optical observations

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