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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"

26497 results found.

  1. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 260917A: Glowbug gamma-ray detection
  3. GRB 260915A: SVOM/ECLAIRs refined analysis
  4. GRB 260917B: WINTER J-band observations
  5. GRB 260917B: SVOM/VT optical observations
  6. GRB 260917B: LCO optical observation
  7. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  8. GRB 260917B: SVOM detection of a faint burst
  9. The EP-WXT trigger 01709317235 is likely a flaring star
  10. GRB 260915A: J-band upper limit with WINTER
  11. GRB 260909A: NOEMA detection
  12. GRB 260914A: SVOM/GRM observation
  13. GRB 260914A: Mondy and TShAO optical observations
  14. GRB 260914A: SVOM/ECLAIRs refined analysis
  15. GRB 260909A: Swift-XRT observations
  16. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  17. GRB 260915A: SVOM/C-GFT optical upper limits
  18. GRB 260915A: EP-FXT follow-up observation
  19. GRB 260915A: SVOM/VT refined early optical upper limits
  20. GRB 260915A: REM optical/NIR observations
  21. GRB 260914A: REM optical/NIR observations
  22. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  23. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  24. GRB 260915A: NOT optical upper limit
  25. GRB 260915A: SVOM/VT optical upper limits from VHF data
  26. GRB 260915A: LCO optical upper limits
  27. GRB 260914A: EP-FXT follow-up observation
  28. GRB 260915A: SVOM detection of a burst
  29. GRB 260914A: LCO optical observation
  30. GRB 260914A: SVOM/C-GFT optical observations
  31. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  32. GRB 260914A: SVOM detection of a burst
  33. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  34. GRB 260818A: Continued ATCA observations
  35. GRB 260913A: SVOM/C-GFT optical upper limit
  36. GRB 260913A: SVOM detection of a faint burst
  37. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  38. GRB 260907A: SVOM/GRM observation
  39. GRB 260909A: CrAO and AbAO optical upper limits
  40. GRB 260909A: SVOM/ECLAIRs refined analysis
  41. GRB 260910B: GOTO tentative optical counterpart candidates
  42. GRB 260909A: KAIT optical upper limit
  43. GRB 260903A: Swift-XRT observations
  44. GRB 260909A: OHP/T193 z-band upper limit
  45. GRB 260909A: VLT optical and near-infrared upper limits
  46. GRB 260909A: EP-FXT follow-up observation
  47. EP260806a: NOEMA detection
  48. EP260623a: NOEMA detections
  49. GRB 260909A: SVOM/GRM observation
  50. GRB 260909A: Mondy optical observations and afterglow candidate
  51. GRB 260909A: Xinglong 2.16m optical upper limit
  52. GRB 260909A: SVOM/C-GFT optical upper limit
  53. GRB 260909A: SVOM detection of a burst
  54. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  55. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  56. GRB 260903A: SAO RAS optical upper limit
  57. The EP-WXT trigger 01709305715 is likely a flaring star
  58. EP260903a: EP-FXT follow-up observation
  59. The EP-WXT trigger 01709302592 is likely a flaring star
  60. GRB 260903A: J-band upper limit with WINTER
  61. GRB 260903A: SVOM/ECLAIRs refined analysis
  62. GRB260903A: Liverpool Telescope optical observations
  63. GRB 260903A: SAO RAS optical observations
  64. GRB 260830A: GECAM-B detection of a burst
  65. EP260903a: EP-WXT detection of a fast X-ray transient
  66. GRB 260903A: EP-FXT follow-up observation
  67. GRB 260903A: OHP/T193 optical afterglow detection
  68. NuSTAR Transient 260828: SOAR Optical Upper Limits
  69. GRB 260903A: SVOM/VT optical candidate
  70. GRB 260903A: Retraction of optical counterpart of GCN 45501
  71. GRB 260831A: GECAM-B observation
  72. GRB 260903A: LCO optical counterpart detection
  73. GRB 260903A: SVOM detection of a soft faint burst
  74. EP260901a: SVOM/VT optical upper limits
  75. EP260901a: EP-FXT follow-up observation
  76. Konus-Wind detection of GRB 260829A
  77. GRB 260829A: SVOM/GRM observation
  78. GRB 260818A: ATCA detection of a candidate radio counterpart
  79. EP260830a: EP-FXT follow-up observation
  80. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  81. NuSTAR Transient 260828: LCO Optical Upper Limits
  82. EP260901a: EP-WXT detection of a fast X-ray transient
  83. GRB 260829A: AstroSat CZTI detection
  84. GRB 260831B: EP-FXT follow-up observation
  85. GRB 260831B: LCO optical upper limits
  86. EP260830a: EP-WXT detection of a fast X-ray transient
  87. GRB 260827A: SVOM/GRM observation
  88. NuSTAR 260828: a 1100s hard X-ray transient
  89. GRB 260831B: SVOM detection of a possible burst
  90. GRB 260827A: Glowbug gamma-ray detection
  91. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  92. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  93. GRB 260829A: GECAM-B observation of a long burst
  94. GRB 260825A: SVOM/GRM observation of a long burst
  95. GRB 260829A: Fermi GBM Detection
  96. GRB 260825A: AstroSat CZTI detection
  97. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  98. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  100. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube

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