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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"

28053 results found.

  1. EP260830a: EP-FXT follow-up observation
  2. EP260901a: Global MASTER-Net observations report
  3. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  4. NuSTAR Transient 260828: LCO Optical Upper Limits
  5. EP260901a: EP-WXT detection of a fast X-ray transient
  6. GRB 260830A: NuSTAR detection of prompt emission
  7. GRB 260831B: LCO optical upper limits
  8. EP260830a: Global MASTER-Net observations report
  9. EP260830a: EP-WXT detection of a fast X-ray transient
  10. GRB 260827A: SVOM/GRM observation
  11. NuSTAR 260828: a 1100s hard X-ray transient
  12. GRB 260831B: SVOM detection of a possible burst
  13. GRB 260827A: Glowbug gamma-ray detection
  14. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  15. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  16. GRB 260825A: SVOM/GRM observation of a long burst
  17. GRB 260829A: Fermi GBM Detection
  18. GRB 260825A: AstroSat CZTI detection
  19. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  20. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  21. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  22. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 260818B: Further EP-FXT observation
  24. GRB 260818B: VLT optical and nIR observations
  25. GRB 260818B: TNG NIR observations
  26. MAXI GRB260827.40: Global MASTER-Net observations report
  27. GRB 260818B: 6 GHz VLA observations
  28. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  29. GRB 260808B: SAO RAS observations of the optical rebrightening
  30. EP260822a: Global MASTER-Net observations report
  31. EP Alert 260820.31: Global MASTER-Net observations report
  32. GRB 260807A: EP-FXT follow-up observations
  33. IceCube Alert 260825A: Global MASTER-Net observations report
  34. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  35. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  36. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  37. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  38. EP260822a: EP-FXT non-detection and upper limit
  39. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  40. EP260822a: Einstein Probe detection of a fast X-ray transient
  41. GRB 260822A: LCO optical upper limits
  42. GRB 260822A: GROWTH-India Telescope Upper Limits
  43. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  44. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  45. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 260818B: VLA radio observations
  47. GRB 260818B: SVOM/C-GFT optical upper limit
  48. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  49. IceCube Alert 260821A: Global MASTER-Net observations report
  50. GRB 260820A: Insight-HXMT/HE detection
  51. EP detected a brightening of LMXB 1ES 1735-26.9
  52. GRB 260818A: J-band observations with WINTER
  53. GRB 260818A: SVOM/ECLAIRs refined analysis
  54. GRB 260818B: NOT optical upper limits
  55. GRB 260810A: SVOM/GRM observation
  56. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  57. GRB 260818B: LCO optical upper limits
  58. GRB 260818B: SVOM detection of a short burst
  59. EP260806a: SAO RAS multicolor optical observations
  60. GRB 260818A: LCO optical upper limits
  61. EP260812a: AbAO optical upper limit
  62. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  63. GRB 260810A: Insight-HXMT/HE detection
  64. GRB 260818A: SVOM possible detection of a long and faint GRB
  65. EP260806a: NUTTELA-TAO optical observations
  66. The EP-WXT trigger 01709281429 is likely a flaring star
  67. EP260812a: AZT-22 optical upper limit
  68. EP260806a: WFST optical observations
  69. EP260812b: Optical upper limit with Kinder
  70. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  71. GRB 260808B: Liverpool Telescope further optical observations
  72. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  73. EP260812a: NOT and Liverpool Telescope upper limits:
  74. EP260812b: Liverpool Telescope observations
  75. EP260812b: GOTO detection of the optical counterpart
  76. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  77. EP260812a: SVOM/C-GFT optical upper limit
  78. EP260812b: COLIBRÍ optical observations
  79. EP260812b: SVOM/VT optical observation
  80. GRB 260808A: SVOM/GRM observation
  81. EP260812b: Einstein Probe detection of an X-ray transient
  82. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  83. Fermi GBM Sub-Threshold Detection of GRB 260809A
  84. GRB 260810A: Glowbug gamma-ray detection
  85. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  86. GRB 260810A: AstroSat CZTI detection of a long burst
  87. EP260812a: Einstein Probe detection of an X-ray transient
  88. GRB 260809A: SAO RAS optical observations
  89. GRB 260808B: SAO RAS optical observations
  90. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  91. EP260806a: MAO/AZT-22 optical observations
  92. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  93. GRB260808B: MAO/AZT-22 optical observations
  94. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  95. GRB 260809A: J-band upper limit with WINTER
  96. GRB 260806A: Glowbug gamma-ray detection
  97. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  98. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  99. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  100. GRB 260809A: NOT optical observations

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