Radiocarbon calibration requires a calibration curve: an estimate of the true calendar age associated with a radiocarbon measurement. The following curves are included with the c14 package:

- IntCal20
IntCal Northern Hemisphere curve, 0–55,000 cal BP Reimer2020c14.

- SHCal20
IntCal Southern Hemisphere curve, 0–55,000 cal BP Hogg2020c14.

- Marine20
IntCal marine curve, 0–55,000 cal BP Heaton2020c14.

- IntCal13, IntCal09, IntCal04, IntCal98
Previous IntCal Northern Hemisphere curves Reimer2013,Reimer2009,Reimer2004,Stuiver1998c14. Superseded by

`IntCal20`

.- SHCal13, SHCal04
Previous IntCal Southern Hemisphere curves Hogg2013,McCormac2004c14. Superseded by

`SHCal20`

.- Marine13, Marine09, Marine04, Marine98
Previous IntCal marine curves Reimer2013,Reimer2009,Hughen2004,Stuiver1998c14. Superseded by

`Marine20`

.

Generally, it is recommended to use the latest curve from the IntCal series:
`IntCal20`

for samples from the northern hemisphere; `SHCal20`

for samples
from the southern hemisphere; or `Marine20`

for samples that obtained their
14C in a marine environment.

## Usage

```
IntCal20
SHCal20
Marine20
IntCal13
SHCal13
Marine13
IntCal09
Marine09
IntCal04
SHCal04
Marine04
IntCal98
Marine98
```

## Format

A c14_curve object with the following fields.

For standard curves:

- cal_age
Calendar ages with associated era (era::yr class).

- c14_age
Uncalibrated radiocarbon ages.

- c14_error
Errors (sigma values) associated with

`c14_age`

.- d14c
Delta-14C values.

- d14c_error
Errors (sigma values) associated with

`d14c`

.

For post-bomb curves:

- cal_age
Calendar ages with their associated era (era::yr class).

- f14c
Fraction modern (F14C or pMC) values.

- f14c_error
Errors (sigma values) associated with

`f14c`

.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 9501.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 9501.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 5501.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 5141.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 5141.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 4801.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 3522.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 3651.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 3302.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 2482.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 3301.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 1538.

An object of class `c14_curve_14c`

(inherits from `c14_curve`

, `vctrs_rcrd`

, `vctrs_vctr`

) of length 1569.