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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

21135 results found.

  1. GRB 210217A: Swift/UVOT Detection
  2. GRB 210222B: MASTER OT observation
  3. GRB 210222B: NEXT early optical afterglow observations
  4. GRB 210222B: GOTO confirmation of afterglow detection
  5. GRB210222B: BOOTES-1 optical afterglow detection
  6. Swift GRB210222.94: Global MASTER-Net observations report
  7. GRB 210218A: Swift-XRT observations
  8. uGMRT radio detection of GRB 210204A
  9. GRB 210212A: Lowell Discovery Telescope observations
  10. GRB 210217A: Liverpool Telescope First Hour Observations
  11. GRB 210217A: KAIT Optical Observations
  12. GRB 210218A: NEXT optical upper limit
  13. ZTF21aakruew/AT2021cwd: GROND observations
  14. GRB 210212A: REM early-time optical/NIR upper limits
  15. GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
  16. GRB 210217A: NEXT early optical afterglow observations
  17. GRB 210212A: Mondy optical observations
  18. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Assy and Mondy optical observations
  19. IceCube-210210A: Two Additional Optical Candidate Counterparts Found by DECam
  20. GRB 210208A: 1.3m DFOT Optical upper limit
  21. GRB 210211A: ePESSTO+ NTT optical observations
  22. GRB 210212B: Swift ToO observations
  23. GRB 210212B (TF21aakruew/AT2021cwd): Assy optical observations
  24. GRB 210212A: 1.3m DFOT Optical upper limit
  25. GRB 210212A: Gemini South optical observations
  26. Fermi GRB 210213A: Global MASTER-Net observations report
  27. IceCube Alert 210213.78: Global MASTER-Net observations report
  28. IceCube-210210A: Four Candidate Optical Counterparts from DECam Observations
  29. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  30. GRB 210212A: Possible host galaxy counterpart with the NOT
  31. Swift GRB 210212A: Global MASTER-Net observations report
  32. GRB 210212A: Swift/UVOT Upper Limits
  33. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  34. GRB 210210A : 1.3m DFOT optical observations
  35. GRB 210211A: Swift/UVOT Detection
  36. Swift-XRT observations of IceCube-210210A
  37. GRB 210211A: MASTER optical observation of REM OT
  38. GRB 210210A: CAHA detection and likely jet break
  39. GRB 210211A: REM optical/NIR afterglow detection
  40. Fermi-LAT Gamma-ray Observations of IceCube-210210A
  41. Swift GRB210211.36: Global MASTER-Net observations report
  42. Fermi trigger No 634659312: Global MASTER-Net observations report
  43. IceCube Alert 210210.50: Global MASTER-Net observations report
  44. Fermi GRB 210210B: Global MASTER-Net observations report
  45. IceCube-210210A: Upper limits from Fermi-GBM Observations
  46. IceCube-210210A: Two Candidate Counterparts from the Zwicky Transient Facility
  47. Swift GRB 210209A: Global MASTER-Net observations report
  48. GRB 210210A: Swift/UVOT Detection
  49. GRB 210112A: LBT host detection and correction to GCN 29319 (CAHA observations)
  50. GRB 210209A: Swift/UVOT Upper Limits
  51. GRB 210210A: MASTER afterglow observation
  52. ZTF21aahifke/AT2021clk: ZTF discovery of an optical fast transient (possible afterglow)
  53. Swift GRB 210210A: Global MASTER-Net observations report
  54. GRB 210207B: Continued LCO Observations
  55. GRB 210104A: LBT observations
  56. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Mondy optical observations
  57. GRB 210207B: Swift/UVOT Detection
  58. GRB 210204A: LBT observations and jet break
  59. GRB 210207B: LCO Optical Afterglow Detection
  60. GRB 210207B: KAIT Optical Observations
  61. GRB 210207B: AGILE observations
  62. GRB 210207B: AbAO optical upper limit
  63. GRB 210207B: optical detection with 3.6m Devasthal Optical Telescope
  64. Fermi GRB 210207A: Global MASTER-Net observations report
  65. GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
  66. GRB 210204A: Optical Observations from HCT
  67. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  68. GRB 210204A: Swift ToO observations
  69. VLT/X-shooter redshift of 1.466 for ZTF21aagwbjr/AT2021buv, strengthening its association with GRB 210204A
  70. GRB 210205A: Swift/UVOT Upper Limits
  71. Swift GRB 210205A: Global MASTER-Net observations report
  72. Fermi GRB 210204B: Global MASTER-Net observations report
  73. Fermi GRB 210204A: Global MASTER-Net observations report
  74. Fermi GBM Observations of a bright burst from SGR J1935+2154
  75. Fermi GRB 210202A: Global MASTER-Net observations report
  76. Fermi trigger No 633963272: Global MASTER-Net observations report
  77. Fermi trigger No 633879387: Global MASTER-Net observations report
  78. GECAM observations of SGR 1935+2154
  79. Continued Chandra observations of GW170817 at ~3.3 years since merger
  80. Fermi GBM Observations of SGR J1935+2154
  81. ZTF21aaeyldq: Observations with the 3.6m DOT
  82. GRB 210120A: Fermi GBM detection
  83. Fermi trigger No 633348010: Global MASTER-Net observations report
  84. HAWC Transient event on 2021/01/25
  85. Fermi trigger No 633257525: Global MASTER-Net observations report
  86. GRB 210120A : 1.3m DFOT optical observations
  87. ZTF21aaeyldq: GROND and CAHA jet break confirmation
  88. ZTF20aaeyldq: VLA radio detection
  89. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  90. GRB 210120A: MASTER OT (possibly) discovery
  91. GRB 210104A: 3.6m DOT optical upper limit
  92. Fermi GRB 210120A: Global MASTER-Net observations report
  93. GRB 210112A: 3.6m DOT optical detection
  94. ZTF21aaeyldq: GROND observations
  95. ZTF21aaeyldq: LBT near-infrared observations
  96. Fermi GRB 210119A: Global MASTER-Net observations report
  97. ZTF21aaeyldq CAHA 2.2m detection and power-law decay
  98. Fermi trigger No 632573937: Global MASTER-Net observations report
  99. ZTF21aaeyldq: KPED observations
  100. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT

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