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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"

26488 results found.

  1. GRB 260822A: SVOM/ECLAIRs refined analysis
  2. GRB 260809A: SVOM/ECLAIRs refined analysis
  3. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  5. GRB 260822A: EP/FXT follow-up observations
  6. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  7. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  8. EP260822a: EP-FXT non-detection and upper limit
  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. GRB 260822A: GROWTH-India Telescope Upper Limits
  14. GRB 260822A: SVOM detection of a short burst
  15. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  16. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  17. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 260818B: SVOM/C-GFT optical upper limit
  19. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  20. The EP-WXT trigger 01709286204 is likely a flaring star
  21. GRB 260818B: SVOM/GRM observation
  22. EP detected a brightening of LMXB 1ES 1735-26.9
  23. GRB 260818B: EP-FXT follow-up observation
  24. GRB 260818A: J-band observations with WINTER
  25. GRB 260818B: SVOM/ECLAIRs refined analysis
  26. GRB 260818A: SVOM/ECLAIRs refined analysis
  27. GRB 260818B: NOT optical upper limits
  28. GRB 260810A: SVOM/GRM observation
  29. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  30. GRB260818A: EP-FXT follow-up observation
  31. GRB 260818B: LCO optical upper limits
  32. GRB 260818B: SVOM detection of a short burst
  33. EP260806a: SAO RAS multicolor optical observations
  34. GRB 260818A: LCO optical upper limits
  35. EP260812a: AbAO optical upper limit
  36. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 260818A: SVOM possible detection of a long and faint GRB
  38. EP260806a: SVOM/ECLAIRs detection through targeted search
  39. EP260806a: NUTTELA-TAO optical observations
  40. The EP-WXT trigger 01709281429 is likely a flaring star
  41. EP260812a: AZT-22 optical upper limit
  42. EP260806a: WFST optical observations
  43. The EP-WXT trigger 01709280562 is likely a flaring star
  44. EP260812b: Optical upper limit with Kinder
  45. The EP-WXT trigger 01709279838 is likely a flaring star
  46. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  47. GRB 260808B: Liverpool Telescope further optical observations
  48. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  49. EP260812a: NOT and Liverpool Telescope upper limits:
  50. EP260812b: Liverpool Telescope observations
  51. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  52. EP260812a: SVOM/C-GFT optical upper limit
  53. EP260812b: COLIBRÍ optical observations
  54. EP260812b: SVOM/VT optical observation
  55. GRB 260808A: SVOM/GRM observation
  56. EP260812b: Einstein Probe detection of an X-ray transient
  57. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  58. GRB 260810A: Glowbug gamma-ray detection
  59. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  60. GRB 260810A: AstroSat CZTI detection of a long burst
  61. EP260812a: Einstein Probe detection of an X-ray transient
  62. GRB 260809A: SAO RAS optical observations
  63. GRB 260808B: SAO RAS optical observations
  64. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  65. GRB 260808A: GECAM-B observation
  66. GRB 260807A: SVOM/ECLAIRs refined analysis
  67. EP260806a: MAO/AZT-22 optical observations
  68. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB260808B: MAO/AZT-22 optical observations
  70. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  71. GRB 260809A: J-band upper limit with WINTER
  72. GRB 260806A: Glowbug gamma-ray detection
  73. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  74. The EP-WXT trigger 01709278015 is likely a flaring star
  75. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  76. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  77. GRB 260809A: NOT optical observations
  78. GRB260809A: MAO/AZT-22 optical observations
  79. GRB260809A: OHP/T193 optical observations
  80. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  81. EP260809a: J-band upper limit with WINTER
  82. GRB 260808B: J-band upper limit with WINTER
  83. GRB 260808B: SVOM/ECLAIRs refined analysis
  84. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  85. GRB 260809A: SVOM detection of a faint burst
  86. GRB 260808B: Liverpool Telescope optical observations
  87. GRB 260808B: NOT optical observations
  88. GRB 260808B: LCO optical observations
  89. EP260809a: COLIBRÍ optical observations
  90. EP260809a: LCO optical observation
  91. EP260809a: OHP/T193 optical observations
  92. GRB260808B: OHP/T193 optical observations
  93. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  94. EP260809a: Einstein Probe detection of an X-ray transient
  95. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  96. GRB 260808B: SVOM/VT optical candidate from VHF data
  97. GRB 260808B: SVOM detection of a faint burst
  98. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 260807A: SVOM possible detection of a faint burst
  100. EP260806a: COLIBRÍ optical observations

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